A reformulation of Murashige and Skoog medium (WPBS medium) improves embryogenesis, morphogenesis and transformation efficiency in temperate and tropical grasses and cereals

Slow callus growth is a barrier to efficient genetic transformation in some gramineous species. A reformulation of Murashige and Skoog (MS) medium, with additional magnesium sulphate, potassium phosphate, copper sulphate, proline and glutamine, termed WPBS medium, has been developed which improves all aspects of in vitro culture when compared with MS based media. Embryogenic callus could be produced more rapidly from responsive genotypes of sixteen cereal, forage, model and energy grass species, whether using embryos, shoot tips or proliferated meristems as explants. Three species were not transformed due to contamination or unsuitable explant, but thirteen species were transformed using an identical Agrobacterium-mediated transformation, selection and regeneration protocol, including Avena sativa and Oryza sativa. Readily transformable species such as Lolium perenne, Brachypodium distachyon and Festuca arundinacea and recalcitrant species such as Lolium temulentum and Miscanthus sinensis were reliably transformed, while two new species Phalaris arundinacea and viviparous Deschampsia cespitosa were transformed at the first attempt. It is hoped that the use of WPBS media and this general transformation protocol may help to improve the efficiency of grass and cereal transformation.

Laparoscopic colorectal surgery - why would you not want to have it and, more importantly, not be trained in it? A consecutive series of 500 elective resections with anastomoses

AIM

We analysed the outcome of a consecutive series of 500 unselected patients who underwent elective laparoscopic colorectal resection with anastomosis (ELCRA) under the care of a single surgeon.

METHOD

A prospectively collected electronic database of all laparoscopic procedures conducted from April 2001 to September 2008 was analysed.

RESULTS

A total of 500 ELCRAs were performed [230 male and 270 female patients; mean age 65.6 years (range 19-93 years; American Society of Anesthesiologists grade I (103), II (246), III (145) and IV (6)]. Of these, 217 patients underwent high anterior resection. A total of 131 total mesorectal excisions (55 covering ileostomies), 152 right/extended right resections and 240 operations were performed by trainees under supervision. The indications for surgery included cancer (340), diverticular disease (96), Crohn's disease (40) and polyps (24). Mean operating time was 115 min (range 35-550 min). There were eight (1.6%) conversions. The mean length of hospital stay was 5.2 days (median 4 days). A total of 93 (18.6%) patients had an inpatient complication, including ileus (22), wound infection (14), anastomotic leakage (12), enterotomy (2), 'off-screen' enterotomy (2), abscess (3), ureteric injury (1), cardiac arrhythmia (12), myocardial infarction (5), pulmonary embolus (4), pneumonia (1), Clostridium difficile (3) and retention of urine (9). There were 20 (4%) readmissions for complications, including ileus (4), urinary retention (3), abscess formation (2) and leakage (2). The 30-day mortality was nine of 500 (1.8%) following anastomotic leakage (3), duodenal enterotomy (1), bleeding duodenal ulcer (1), C. difficile infection (1) and cardiac complications (3).

CONCLUSION

This unselected cohort of patients (the largest single surgeon series in the UK) demonstrates that in trained hands low conversion and complication rates can be consistently achieved.

Competency in laparoscopic colorectal surgery is achievable with appropriate training but takes time: a comparison of 300 elective resections with anastomosis

AIM

The aim of this retrospective cohort study was to compare outcomes in patients who underwent elective laparoscopic colorectal resection with anastomosis performed by a single surgeon or his training fellow.

METHOD

A prospective electronic database of all laparoscopic procedures between January 2005 and September 2008 was used. Two groups were compared; those patients operated upon by the Consultant trainer (C) and those by seven supervised Fellows (F). Fellows were either post CCT or in their last year of training. Three hundred consecutive patients undergoing laparoscopic colorectal resection with anastomosis were examined, 150 in each group. Groups were matched for indication, age, American Society of Anesthesiology (ASA) grade, cancer T stage and resection performed. Preoperative work-up, operative surgery and anaesthesia were identical between groups.

RESULTS

No significant difference was demonstrated in age, mean 67 (26-91) or ASA grade. Indications for surgery were; cancer (C) 120, (F) 126, diverticular disease (C) 22, (F) 20, Crohn's disease (C) 8, (F) 7. Fellow's mean operative time was significantly longer at 123 min (95%CI 117-134) compared to the consultant trainer -105 min. (95%CI 98-111): P < 0.01). No significant differences in the complication or conversion rates were demonstrated. Length of stay and the 30-day readmission rates were similar.

CONCLUSION

In this retrospective cohort study we have demonstrate that when matched patients are compared, supervised trainee operating time is significantly longer than that of the consultant trainer but without any significant increase in length of stay, complication or readmission rates. Training to a level of competency takes time but not at the expense of patient care.

Routine magnetic resonance cholangiopancreatography and intra-operative cholangiogram in the evaluation of common bile duct stones

INTRODUCTION

Magnetic resonance cholangiopancreatography (MRCP) is a safe and sensitive investigation for the imaging of common bile duct pathology. When used to exclude common bile duct (CBD) stones, MRCP may obviate the need for intra-operative cholangiogram (IOC). In this prospective study, we looked at the single centre results of patients who underwent cholecystectomy with IOC following pre-operative MRCP.

PATIENTS AND METHODS

Over a period of 18 months, 69 patients (24 male and 45 female; mean age 59 years [range, 19-86 years]) were investigated by MRCP prior to cholecystectomy. All patients underwent IOC. Inclusion criteria for MRCP consisted of derangement of liver function tests and/or history of jaundice in cases of ultrasound-proven cholelithiasis.

RESULTS

Sixteen patients had suspected stones or filling defects on MRCP; all but two of these were confirmed to be stones on IOC. In only one patient was a stone visualised on IOC and not seen on MRCP.

CONCLUSION

MRCP may be the only pre-operative investigation needed for exclusion of CBD stones, obviating the necessity for IOC.

Routine magnetic resonance cholangiopancreatography and intra-operative cholangiogram in the evaluation of common bile duct stones

INTRODUCTION

Magnetic resonance cholangiopancreatography (MRCP) is a safe and sensitive investigation for the imaging of common bile duct pathology. When used to exclude common bile duct (CBD) stones, MRCP may obviate the need for intra-operative cholangiogram (IOC). In this prospective study, we looked at the single centre results of patients who underwent cholecystectomy with IOC following pre-operative MRCP.

PATIENTS AND METHODS

Over a period of 18 months, 69 patients (24 male and 45 female; mean age 59 years [range, 19-86 years]) were investigated by MRCP prior to cholecystectomy. All patients underwent IOC. Inclusion criteria for MRCP consisted of derangement of liver function tests and/or history of jaundice in cases of ultrasound-proven cholelithiasis.

RESULTS

Sixteen patients had suspected stones or filling defects on MRCP; all but two of these were confirmed to be stones on IOC. In only one patient was a stone visualised on IOC and not seen on MRCP.

CONCLUSION

MRCP may be the only pre-operative investigation needed for exclusion of CBD stones, obviating the necessity for IOC.

Genetic transformation of Dichanthium annulatum (Forssk)--an apomictic tropical forage grass

Eleven Dichanthium annulatum (Forssk) plants were regenerated from embryogenic callus co-transformed with two plasmids encoding either the hygromycin phosphotransferase gene (hph) or the beta-glucuronidase (GUS) gene (uidA). Analysis of these putative transformants showed that three plants were transformed with the hph gene, showed the presence of the hph transcript and expressed hygromycin resistance after transfer to soil. Two of these also contained the uidA gene but did not express GUS and were shown to be the same transformation event. All three of the transformants set seed. Hygromycin resistance varied from 68-100% in the progeny of the three transformants. Transgene transmission appeared to have been mainly through apomixis.

Agrobacterium tumefaciens-mediated transformation of Festuca arundinacea (Schreb.) and Lolium multiflorum (Lam.)

Agrobacterium tumefaciens strain LBA4404 carrying plasmid pTOK233 encoding the hygromycin resistance (hph) and beta-glucuronidase (uidA) genes has been used to transform two agronomic grass species: tall fescue (Festuca arundinacea) and Italian ryegrass (Lolium multiflorum). Embryogenic cell suspension colonies or young embryogenic calli were co-cultured with Agrobacterium in the presence of acetosyringone. Colonies were grown under hygromycin selection with cefotaxime and surviving colonies plated on embryogenesis media. Eight Lolium (six independent lines) and two Festuca plants (independent lines) were regenerated and established in soil. All plants were hygromycin-resistant, but histochemical determination of GUS activity showed that only one Festuca plant and one Lolium plant expressed GUS. Three GUS-negative transgenic L. multiflorum and the two F. arundinacea plants were vernalised and allowed to flower. All three Lolium plants were male- and female-fertile, but the Festuca plants failed to produce seed. Progeny analysis of L. multiflorum showed a 24-68% inheritance of the hph and uidA genes in the three lines with no significant difference between paternal and maternal gene transmission. However, significant differences were noted between the paternal and maternal expression of hygromycin resistance.

Particle-inflow-gun-mediated genetic transformation of buffel grass (Cenchrus ciliaris L.): optimizing biological and physical parameters

The present study was conducted to optimize various biological and physical parameters for developing an efficient and reproducible gene transfer method for genetic transformation of buffel grass. Transformation was carried out using a helium-driven particle inflow gun (PIG). Embryogenic calli produced from mature seeds of buffel grass cv. CC-119 were separately bombarded with four plasmids, containing Actin (pAct1DX), Ubiquitin (pAHC-25; pAHC-27) and CaMV-35S (pCaMVGUS) promoters, coated on tungsten and gold particles. The efficiency of transformation was monitored through transient GUS expression. Different parameters, viz., the type of promoter, type and size of microcarrier, helium gas pressure, distance and time of bombardment, were standardized for delivering DNA into embryogenic calli. Bombardment with plasmid DNA carrying the actin promoter coated on 1.6 micro gold particles, at a helium pressure of 4 bars, a distance of 10 cm for 10 micro sec and 28 mm Hg vacuum in the chamber, produced the best result in transient GUS expression. The Actin promoter was found to be more efficient in driving expression of the GUS gene in buffel grass, followed by Ubiquitin and CaMV-35S promoters. Lower helium pressure was found to be sub-optimal, while higher pressure produced a smaller number of blue spots, probably due to excessive damage to the cells. Maximum of 385 blue spots was observed with gold particles of 1.6 micro size, whereas only 213 blue spots were recorded for tungsten particles of 1.0 micro size. The optimized parameters can be employed for genetic transformation of buffel grass with genes of agronomic importance.

Exacerbation of atopic dermatitis after bacillus Calmette-Guérin vaccination

In two children with atopic dermatitis, routine vaccination with bacillus Calmette-Guérin (BCG) was followed by severe exacerbation of skin disease. If the sequence is cause and effect, a possible mechanism is stimulation of a Th2 lymphocyte cytokine profile by the vaccine, with migration of activated lymphocytes to inflamed skin. In children with active atopic dermatitis, BCG vaccination is best deferred until remission.

Stability at the phosphoglucoisomerase (PGI/2) locus in Lolium multiflorum (2n = 4x = 28) × Festuca arundinacea (2n = 6x = 42) plants regenerated from cell suspension

Plants were regenerated from a cell suspension from shoot-tip derived callus of a pentaploid Lolium multiflorum (2n = 4x = 28) × Festuca arundinacea (2n = 6x = 42) in which a set of five homologous and homoeologous chromosomes were marked at the PGI/2 locus by distinct alleles. A direct relationship was found in regenerated plants between time in cell suspension and the number of aberrations at the PGI/2 locus. These included deletion of any one, and in a few cases two, of the five PGI/2 alleles, but these were not always related to chromosome loss. In addition three different PGI/2 alleles were each rendered null in some somaclones regenerated last from the cell suspension. While bivalent and trivalent frequency remained unaltered in the regenerated plants compared with the original hybrid, univalent frequency decreased. Chromosome configurations of four or more chromosomes, which probably represent intergeneric chromosome pairing, were significantly increased in the regenerated plants compared with the original hybrid and were negatively correlated with univalents. The possible incorporation of a cell culture phase as a way of increasing intergeneric recombination between L. multiflorum and F. arundinacea chromosomes in a conventional breeding program is discussed.Key words: Festuca–Lolium, somaclonal variation, phosphoglucoisomerase (PGI/2), chromosome instability, somatic recombination.

Stability at the phosphoglucoisomerase (PGI/2) locus in Festuca arundinacea plants regenerated from cell suspension and protoplast culture

A study was made of the phosphoglucoisomerase (PGI/2) phenotype of plants regenerated from suspension and protoplast culture originating from a Festuca arundinacea (2n = 6x = 42) plant with distinct PGI/2 phenotype. Of the regenerated plants from suspension culture, 20 were abnormal in that they deviated from the PGI/2 phenotype of the donor plant. Among the abnormal plants two distinct isozyme variants absent in the original donor, which were probably the result of point mutations, were recorded. There was evidence of deletions of specific PGI/2 alleles. This was confirmed cytologically by the reduced chromosome number found in the relevant cell suspension derived plants. There was also evidence that an active allele had been transformed into a null allele. All the plants regenerated from protoplast culture had the same PGI/2 phenotype as the donor plant but were hyperpolyploid. The loss of activity of individual PGI/2 alleles in plants derived from protoplasts was masked by gene duplication because of their hyperpolyploid nature. A high degree of instability was identified in nonregenerating calli. It was thought that abnormalities in the nonregenerating calli were affecting their potential to regenerate plants.Key words: Festuca arundinacea, somaclonal variation, phosphoglucoisomerase (PGI/2), chromosome instability, point mutations.

Polysaccharide production in liquid cell suspension cultures of Phleum pratense L

The production of carbohydrates by cell suspension cultures of Phleum pratense (timothy grass) is described. Extracellular polysaccharides similar in monosaccharide composition to native cell wall polymers were accumulated, together with polymers of fructose (fructans). The fructans had similar properties to the intracellular reserve polymers found in intact plants, and were found in both cells and media of young, slow-growing cultures.Production of extracellular polysaccharides differed in cultures grown on sucrose or equimolar glucose/fructose as carbon source. These differences were observed only when autoclaved media were used, and were not related to changes in either pH or osmolarity. Autoclaving medium containing radioactive glucose and fructose produced a novel, unidentified labelled compound which was absent in medium containing labelled sucrose.