Efficient and genotype independent maize transformation using pollen transfected by DNA-coated magnetic nanoparticles.

Current gene delivery methods for maize are limited to specific genotypes and depend on time-consuming and labor-intensive tissue culture techniques. Here, we report a new method to transfect maize that is culture-free and genotype independent. To enhance efficiency of DNA entry and maintain high pollen viability of 32%-55%, transfection was performed at cool temperature using pollen pretreated to open the germination aperture (40%-55%). Magnetic nanoparticles (MNPs) coated with DNA encoding either red fluorescent protein (RFP), ß-glucuronidase gene (GUS), enhanced green fluorescent protein (EGFP) or bialaphos resistance (bar) was delivered into pollen grains, and female florets of maize inbred lines were pollinated. Red fluorescence was detected in 22% transfected pollen grains, and GUS stained 55% embryos at 18 d after pollination. Green fluorescence was detected in both silk filaments and immature kernels. The T1 generation of six inbred lines showed considerable EGFP or GUS transcripts (29%-74%) quantitated by polymerase chain reaction, and 5%-16% of the T1 seedlings showed immunologically active EGFP or GUS protein. Moreover, 1.41% of the bar transfected T1 plants were glufosinate resistant, and heritable bar gene was integrated into the maize genome effectively as verified by DNA hybridization. These results demonstrate that exogenous DNA could be delivered efficiently into elite maize inbred lines recalcitrant to tissue culture-mediated transformation and expressed normally through our genotype-independent pollen transfection system.

[Total thyroidectomy: indications and complications].

OBJECTIVE: To investigate the indications and complications of the total thyroidectomy in the management of thyroid cancer. METHODS: Fifty-one patients with thyroid cancer operated with total thyroidectomy in a period from April 2007 to June 2010, were retrospective analyzed. There were 48 cases of papillary adenocarcinoma, 1 follicular adenocarcinoma, and 2 medullary carcinoma as well, 2 cases with hyperthyroidism, 3 cases with remote metastasis. There were 17 males and 34 females who in their age ranged from 5 years old to 82 years old with a middle age of 50 years old. Among the 45 cases who were initial surgical management patients, there were 17 T1, 13 T2, 7 T3, 8 T4; and there were 31 N0, 11 N1a, 3 N1b, 2 M1. The recurrent laryngeal nerve and the parathyroid gland, and supper laryngeal nerve were exposed routinely. Lymph nodes in Level VI were dissected in all patients, and Level II-IV dissected in 25 patients. ¹³¹I were administrated in 8 patients. RESULTS: Patients were followed up from 1 month to 36 months. There were no patients died and lost of follow up. The two years survival rate was 100.0% (15/15). Pathological examination showed that the multiple focal disease rate was 42.2% (19/45), the cervical lymph nodes metastases rate was 51.0% (26/51). There was no permanent paralysis of recurrent laryngeal nerve and outer branch of supper laryngeal nerve. The permanent hypoparathyroidism rate was 3.9% (2/51). One case with contralateral lymph node metastasis was reoperated and survived without disease. Two cases with remote metastasis were alive with steadied disease. CONCLUSIONS: Under the skilled hand, total thyroidectomy is a safe procedure in the management of thyroid cancer. Totally exposing the parathyroid gland and laryngeal nerve is the key point to prevent the major complications.