288 resultados para CALLUS


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Background The genetic mutation resulting in osteogenesis imperfecta (OI) type V was recently characterised as a single point mutation (c.-14C > T) in the 5' untranslated region (UTR) of IFITM5, a gene encoding a transmembrane protein with expression restricted to skeletal tissue. This mutation creates an alternative start codon and has been shown in a eukaryotic cell line to result in a longer variant of IFITM5, but its expression has not previously been demonstrated in bone from a patient with OI type V. Methods Sanger sequencing of the IFITM5 5' UTR was performed in our cohort of subjects with a clinical diagnosis of OI type V. Clinical data was collated from referring clinicians. RNA was extracted from a bone sample from one patient and Sanger sequenced to determine expression of wild-type and mutant IFITM5. Results: All nine subjects with OI type V were heterozygous for the c.-14C > T IFITM5 mutation. Clinically, there was heterogeneity in phenotype, particularly in the manifestation of bone fragility amongst subjects. Both wild-type and mutant IFITM5 mRNA transcripts were present in bone. Conclusions The c.-14C > T IFITM5 mutation does not result in an RNA-null allele but is expressed in bone. Individuals with identical mutations in IFITM5 have highly variable phenotypic expression, even within the same family.

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Embryogenesis has been induced from endosperm callus cultures of sandalwood (Santalum album L.). Viable plantlets developed from the embryoids on subculture to White's basal medium supplemented with 0.5 mg/l of indole acetic acid. Chromosomal analysis of the root tips showed the triploid number 3n = 30.

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Peanut (Arachis hypogaea L.) lines exhibiting high levels of resistance to peanut stripe virus (PStV) were obtained following microprojectile bombardment of embryogenic callus derived from mature seeds. Fertile plants of the commercial cultivars Gajah and NC7 were regenerated following co-bombardmentwith the hygromycin resistance gene and one of two forms of the PStV coat protein (CP) gene, an untranslatable, full length sequence (CP2) or a translatable gene encoding a CP with an N-terminal truncation (CP4). High level resistance to PStV was observed for both transgenes when plants were challenged with the homologous virus isolate. The mechanism of resistance appears to be RNA-mediated, since plants carrying either the untranslatable CP2 or CP4 had no detectable protein expression, but were resistant or immune (no virus replication). Furthermore, highly resistant, but not susceptible CP2 T0 plants contained transgene-specific small RNAs. These plants now provide important germplasm for peanut breeding, particularly in countries where PStV is endemic and poses a major constraint to peanut production.

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In order to develop an efficient and reliable biolistics transformation system for pineapples parameters need to be optimised for growth, survival and development of explants pre- and post transformation. We have optimised in vitro conditions for culture media for the various stages of plant and callus initiation and development, and for effective selection of putative transgenic material. Shoot multiplication and proliferation is best on medium containing MS basic nutrients and vitamins with the addition of 0.1 mg/L myo-inositol, 20 g/L sucrose, 2.5 mg/L BAP and 3 g/L Phytagel, followed by transfer to basic MS medium for further development. Callus production on leaf base explants is best on MS nutrients and vitamins, to which 10 mg/L of BAP and NAA each was added. Optimum explant age for bombardment is 17-35 week old callus, while a pre-bombardment osmoticum treatment in the medium is not required. By comparing several antibiotics as selective agent, it has been established that a two-step selection of 2 fortnightly sub-cultures on 50 μg/mL of geneticin in the culture medium, followed by monthly sub-cultures on 100 μg/mL geneticin is optimal for survival of transgenic callus. Shoot regeneration from callus cultures is optimal on medium containing MS nutrients and vitamins, 5% coconut water and 400 mg/L casein hydrolysate. Plants can be readily regenerated and multiplied from transgenic callus through organogenesis. Rooting of shoots does not require any additional plant hormones to the medium. A transformation efficiency of 1 – 3.5% can be achieved, depending on the gene construct applied.

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Techniques for the introduction of transgenes to control blackheart by particle bombardment and Agrobacterium co-transformation have been developed for pineapple cv. Smooth Cayenne. Polyphenol oxidase (PPO) is the enzyme responsible for blackheart development in pineapple fruit following chilling injury. Sense, anti-sense and hairpin constructs were used as a means to suppress PPO expression in plants. Average transformation efficiency for biolistics was approximately 1% and for Agrobacterium was approximately 1.5%. These results were considered acceptable given the high regeneration potential of between 80-90% from callus cultures. Southern blot analysis revealed stable integration of transgenes with lower copy number found in plants transformed with Agrobacterium compared to those transformed by biolistics. Over 5000 plants from 55 transgenic lines are now undergoing field evaluation in Australia

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A transformation technique for the introduction of transgenes to control blackheart by particle bombardment has been developed for pineapple cv. Smooth Cayenne. Leaf callus cultures capable of high frequency organogenesis with a short regeneration time were used as explant material. Gus and gfp reporter genes were used to observe and determine transient and stable expression. The ppo gene, isolated from pineapple, was introduced to control blackheart. Co-transformation occurred with constructs containing the nptII gene conferring geneticin resistance. We have recovered 15 independent transgenic gus and gfp lines each from 8 separate experiments and 22 ppo lines from 11 experiments. Gus, gfp, ppo and nptII positive plants have been regenerated, which have been shown by Southern blot analysis to be stable transgenics containing multiple copies of the introduced genes. These results show that biolistic gene delivery in pineapple can be successfully achieved at an acceptable efficiency of 0.21-1.5% for genetic improvement of 'Smooth Cayenne', the industry standard throughout the world.

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Hybrids between Corymbia torelliana (F.Muell.) K.D.Hill & L.A.S.Johnson and C. citriodora subsp. variegata (F.Muell.) A.R.Bean & M.W.McDonald are used extensively to establish forestry plantations in subtropical Australia. Methods were developed for in vitro seed germination, shoot multiplication and plantlet formation that could be used to establish in vitro and ex vitro clone banks of juvenile Corymbia hybrids. Effects of sodium hypochlorite concentration and exposure time on seed contamination and germination, and effects of cytokinin and auxin concentrations on shoot multiplication and subsequent rooting, were assessed. A two-step surface sterilisation procedure, involving 70% ethanol followed by 1% sodium hypochlorite, provided almost no contamination and at least 88% germination. A novel method of cytokinin-free node culture proved most effective for in vitro propagation. Lateral bud break of primary shoots was difficult to induce by using cytokinin, but primary shoots rooted prolifically, elongated rapidly and produced multiple nodes in the absence of exogenous cytokinin. Further multiplication was obtained either by elongating lateral shoots of nodal explants in cytokinin-free medium or by inducing organogenic callus and axillary shoot proliferation with 2.2 µm benzyladenine. Plantlets were produced using an in vitro soil-less method that provided extensive rooting in sterile propagation mixture. These methods provide a means for simultaneous laboratory storage and field-testing of clones before selection and multiplication of desired genotypes.

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Time to first root in cuttings varies under different environmental conditions and understanding these differences is critical for optimizing propagation of commercial forestry species. Temperature environment (15, 25, 30 or 35 +/- A 2A degrees C) had no effect on the cellular stages in root formation of the Slash x Caribbean Pine hybrid over 16 weeks as determined by histology. Initially callus cells formed in the cortex, then tracheids developed and formed primordia leading to external roots. However, speed of development followed a growth curve with the fastest development occurring at 25A degrees C and slowest at 15A degrees C with rooting percentages at week 12 of 80 and 0% respectively. Cutting survival was good in the three cooler temperature regimes (> 80%) but reduced to 59% at 35A degrees C. Root formation appeared to be dependant on the initiation of tracheids because all un-rooted cuttings had callus tissue but no tracheids, irrespective of temperature treatment and clone.

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Time to first root in cuttings varies under different environmental conditions and understanding these differences is critical for optimizing propagation of commercial forestry species. Temperature environment (15, 25, 30 or 352C) had no effect on the cellular stages in root formation of the Slash * Caribbean Pine hybrid over 16 weeks as determined by histology. Initially callus cells formed in the cortex, then tracheids developed and formed primordia leading to external roots. However, speed of development followed a growth curve with the fastest development occurring at 25C and slowest at 15C with rooting percentages at week 12 of 80 and 0% respectively. Cutting survival was good in the three cooler temperature regimes (>80%) but reduced to 59% at 35C. Root formation appeared to be dependant on the initiation of tracheids because all un-rooted cuttings had callus tissue but no tracheids, irrespective of temperature treatment and clone.

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Vegetative propagation programs internationally are affected by the significant decline of rooting success as trees mature. This study compared the cellular stages of root formation in stem cuttings from 15-week-old (juvenile) and 9-y-old (mature) stock plants of the slash x Caribbean pine hybrid (Pinus elliottii var. elliottii x P. caribaea van hondurensis). The cellular stages of root formation were the same in both juvenile and mature cuttings, beginning with cell divisions of the vascular cambium forming callus tissue. Within the callus, tracheids differentiated and elongated to form root primordia. Roots in juvenile cuttings developed faster than those in mature cuttings and the juvenile cuttings had a much higher rooting percent at the end of the study (92% and 26% respectively). Cuttings of the two juvenile genotypes had more primary roots (5.5 and 3.3) than the three mature genotypes (0.96, 0.18 and 0.07). The roots of juvenile cuttings were more evenly distributed around the basal circumference when compared with those on cuttings from the mature genotypes. Further work is needed to improve understanding of physiological changes with maturation so that the rooting success and the speed of development in cuttings from mature stock plants can be optimised, hence improving genetic gain.

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Excised stem, leaf segments and whole flower of the allergenic weed P. hysterophorus were cultured on Murashighe and Skoog's basal medium supplemented with hormones. Shoot buds readily formed in the stem callus cultured on MS Medium supplemented with IAA and BAP or Kinetin. The leaf callus formed roots alone in a wide variety of media. Suspension cultures were initiated from the leaf and stem callus. The leaf callus elicited a positive patch test response for delayed hypersensitivity in 4 patients suffering from Parthenium dermatitis, thus indicating its ability to synthesise the allergenic principle(s).

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Background Although thermal imaging can be a valuable technology in the prevention and management of diabetic foot disease, it is not yet widely used in clinical practice. Technological advancement in infrared imaging increases its application range. The aim was to explore the first steps in the applicability of high-resolution infrared thermal imaging for noninvasive automated detection of signs of diabetic foot disease. Methods The plantar foot surfaces of 15 diabetes patients were imaged with an infrared camera (resolution, 1.2 mm/pixel): 5 patients had no visible signs of foot complications, 5 patients had local complications (e.g., abundant callus or neuropathic ulcer), and 5 patients had difuse complications (e.g., Charcot foot, infected ulcer, or critical ischemia). Foot temperature was calculated as mean temperature across pixels for the whole foot and for specified regions of interest (ROIs). Results No diferences in mean temperature >1.5 °C between the ipsilateral and the contralateral foot were found in patients without complications. In patients with local complications, mean temperatures of the ipsilateral and the contralateral foot were similar, but temperature at the ROI was >2 °C higher compared with the corresponding region in the contralateral foot and to the mean of the whole ipsilateral foot. In patients with difuse complications, mean temperature diferences of >3 °C between ipsilateral and contralateral foot were found. Conclusions With an algorithm based on parameters that can be captured and analyzed with a high-resolution infrared camera and a computer, it is possible to detect signs of diabetic foot disease and to discriminate between no, local, or difuse diabetic foot complications. As such, an intelligent telemedicine monitoring system for noninvasive automated detection of signs of diabetic foot disease is one step closer. Future studies are essential to confirm and extend these promising early findings.

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Recommendations - 1 To identify a person with diabetes at risk for foot ulceration, examine the feet annually to seek evidence for signs or symptoms of peripheral neuropathy and peripheral artery disease. (GRADE strength of recommendation: strong; Quality of evidence: low) - 2 In a person with diabetes who has peripheral neuropathy, screen for a history of foot ulceration or lower-extremity amputation, peripheral artery disease, foot deformity, pre-ulcerative signs on the foot, poor foot hygiene and ill-fitting or inadequate footwear. (Strong; Low) - 3 Treat any pre-ulcerative sign on the foot of a patient with diabetes. This includes removing callus, protecting blisters and draining when necessary, treating ingrown or thickened toe nails, treating haemorrhage when necessary and prescribing antifungal treatment for fungal infections. (Strong; Low) - 4 To protect their feet, instruct an at-risk patient with diabetes not to walk barefoot, in socks only, or in thin-soled standard slippers, whether at home or when outside. (Strong; Low) - 5 Instruct an at-risk patient with diabetes to daily inspect their feet and the inside of their shoes, daily wash their feet (with careful drying particularly between the toes), avoid using chemical agents or plasters to remove callus or corns, use emollients to lubricate dry skin and cut toe nails straight across. (Weak; Low) - 6 Instruct an at-risk patient with diabetes to wear properly fitting footwear to prevent a first foot ulcer, either plantar or non-plantar, or a recurrent non-plantar foot ulcer. When a foot deformity or a pre-ulcerative sign is present, consider prescribing therapeutic shoes, custom-made insoles or toe orthosis. (Strong; Low) - 7 To prevent a recurrent plantar foot ulcer in an at-risk patient with diabetes, prescribe therapeutic footwear that has a demonstrated plantar pressure-relieving effect during walking (i.e. 30% relief compared with plantar pressure in standard of care therapeutic footwear) and encourage the patient to wear this footwear. (Strong; Moderate) - 8 To prevent a first foot ulcer in an at-risk patient with diabetes, provide education aimed at improving foot care knowledge and behaviour, as well as encouraging the patient to adhere to this foot care advice. (Weak; Low) - 9 To prevent a recurrent foot ulcer in an at-risk patient with diabetes, provide integrated foot care, which includes professional foot treatment, adequate footwear and education. This should be repeated or re-evaluated once every 1 to 3 months as necessary. (Strong; Low) - 10 Instruct a high-risk patient with diabetes to monitor foot skin temperature at home to prevent a first or recurrent plantar foot ulcer. This aims at identifying the early signs of inflammation, followed by action taken by the patient and care provider to resolve the cause of inflammation. (Weak; Moderate) - 11 Consider digital flexor tenotomy to prevent a toe ulcer when conservative treatment fails in a high-risk patient with diabetes, hammertoes and either a pre-ulcerative sign or an ulcer on the distal toe. (Weak; Low) - 12 Consider Achilles tendon lengthening, joint arthroplasty, single or pan metatarsal head resection, or osteotomy to prevent a recurrent foot ulcer when conservative treatment fails in a high-risk patient with diabetes and a plantar forefoot ulcer. (Weak; Low) - 13 Do not use a nerve decompression procedure in an effort to prevent a foot ulcer in an at-risk patient with diabetes, in preference to accepted standards of good quality care. (Weak; Low)

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Plant regeneration from mesophyll protoplasts of pepper, Capsicum annuum L. cv. California Wonder has been demonstrated via shoot organogenesis, Protoplasts isolated from fully expanded leaves of 3-week-old axenic shoots when cultured in TM medium supplemented with 1 mgl(-1) NAA, 1 mgl(-1) 2, 4-D, 0.5 mgl(-1) BAP (CM 1) resulted in divisions with a frequency ranging from 20-25%. Antioxidant ascorbic acid and polyvinylpyrrolidone (PVP) in the medium and incubation in the dark helped overcome browning of protoplasts. Microcalli and macrocalli were formed in TM medium containing 2 mgl(-1) NAA and 0.5 mgl(-1) BAP (CM II) and MS gelled medium containing 2 mgl(-1) NAA and 0.5 mgl(-1) BAP (CM III), respectively, Regeneration of plantlets was possible via caulogenesis, Microshoots, 2-5 per callus appeared on MS gelled medium enriched with 0.5 mgl(-1) IAA, 2 mgl(-1) GA and 10 mgl(-1) BAP (CM IVc). Rooting of microshoots was obtained on half strength gelled medium containing 1 mgl(-1) NAA and 0.5 mgl(-1) BAP, Protoplasts isolated from cotyledons failed to divide and degenerated eventually.