(1/6) The auxin-binding protein Nt-ERabp1 alone activates an auxin-like transduction pathway.
Hyperpolarization of tobacco protoplasts is amongst the earliest auxin responses described. It has been proposed that the auxin-binding protein, ABP1, or a related protein could be involved in the first step of auxin perception at the plasma membrane. Using for the first time homologous conditions for interaction between the protein Nt-ERabp1 or a synthetic peptide corresponding to the C-terminus and tobacco protoplasts, we have demonstrated that both can induce the hyperpolarization response. The results show that Nt-ERabp1 or the C-terminal peptide alone activates the auxin pathway from the outer face of the plasma membrane. (+info)
(2/6) Evaluation of surgically retrieved temporomandibular joint alloplastic implants: pilot study.
(3/6) The acceptance of a vitreous carbon alloplastic material, Proplast, in the rabbit eye.
Proplast, a vitreous, carbon-Teflon, fluorocarbon polymer, was tested in rabbits for corneal tolerance and acceptance. Toxicity, vascularization, epithelialization, infection, and extrusion were studied clinically and histologically. Four techniques were used: implantation of irregular-shaped pieces of material in an interlamellar corneal pocket, lamellar graft implantation with one exposed surface, full-thickness corneal implants in a manner similar to penetrating keratoplasty, and full-thickness implants covered by a conjunctival flap. Results showed that Proplast allows fibrovascular ingrowth and stabilization without a significant foreign body response or encapsulation for a period of observation from 6 weeks to 4 months. Evidence of epithelial coverage and epithelial ingrowth was also found. Coverage of the Proplast with conjunctiva or corneal tissue was essential to prevent extrusion and infection. (+info)
(4/6) Use of Proplast II as a subperiosteal implant for the correction of anophthalmic enophthalmos.
BACKGROUND: A variety of autogenous and alloplastic materials have been used as subperiosteal implants to correct anophthalmic enophthalmos. Proplast II is a synthetic porous composite of Teflon polymer and alumina. Proplast II offers a number of advantages over other commonly used alloplastic materials such as silicone and polymethyl methacrylate. It is light, porous, resilient, malleable, and easy to shape. It can be readily sterilised after shaping. It has been found to integrate with the surrounding tissues, thereby minimising the risk of subsequent implant migration and extrusion. METHODS: Proplast II was used as a subperiosteal implant in a total of 15 anophthalmic patients during the period June 1990 to March 1994. The indication for this procedure in all patients was poor orbital volume replacement despite the prior insertion of an adequately sized spherical socket implant. RESULTS: The results were excellent with a good correction of preoperative upper eyelid sulcus deformity. There were no operative complications nor any serious postoperative complications. The implants were well tolerated. CONCLUSION: Proplast II can be highly recommended for use as a subperiosteal implant. (+info)
(5/6) Kinetics of accumulation of citrus tristeza virus RNAs.
Citrus tristeza virus (CTV), a member of the closterovirus group, is one of the more complex single-stranded RNA viruses. The 5' portion of its 19,296-nt, single-stranded RNA genome is expressed as an approximately 400-kDa polyprotein that is proteolytically processed, while the 10 3' open reading frames are expressed from 3'-coterminal subgenomic RNAs (sg RNAs). As an initial examination of the gene expression of this virus, we found that the kinetics of accumulation of genomic and sg RNAs and coat protein of the T36 isolate of CTV were similar in protoplasts of the natural host, citrus, and the experimental nonhost Nicotiana benthamiana. Newly synthesized genomic RNA was detected 2 days postinoculation and increased to a maximum at 3-5 days. The RNA complementary to the full-length virion RNA increased with similar kinetics, but at approximately one-tenth the concentration of genomic plus strands. Most of the abundant sg RNAs also accumulated in parallel to that of the genomic RNA. However, the smallest sg RNA, which corresponds to the p23 gene, increased earlier. The different sg RNAs accumulated in greatly differing amounts, in general with 3'-most sg RNAs accumulating to higher levels than 5' sg RNAs. However, some 3' sg RNAs (p13 and p18) accumulated to low levels. The two 3'-most sg RNAs (p23 and p20) accumulated to high levels approximately equal to that of the genomic RNA. The accumulation curve for coat protein paralleled that of its mRNA, suggesting that its regulation was transcriptional. Progeny virions from protoplasts were used to sequentially infect new protoplasts, serving as a potential source of virus that could evolve free from the genetic selection in intact plants for aphid transmission and movement. (+info)
(6/6) The plant defense response to cucumber mosaic virus in cowpea is elicited by the viral polymerase gene and affects virus accumulation in single cells.
Resistance to infection in cowpea by strains of cucumber mosaic virus (CMV) involves a local, hypersensitive response (HR) and a localization of infection. These responses can be separated by mutation at two sites (nucleotides 1978 and 2007, in codons 631 and 641) in the CMV 2a polymerase gene. Changes to both sites of a restricted strain allow systemic infection without an HR and increase the accumulation of both the 2a protein and viral RNA in protoplasts, while changing position 1978 alone results in a systemic infection, a systemic HR, and an increase in viral RNA accumulation in protoplasts. It is suggested that the inhibition response observed in protoplasts, where an HR does not occur, leads to localization of infection in whole plants and that different plant genes are involved in eliciting the HR and the localization response. (+info)