Genome-wide association analysis for maize stem Cell Wall-bound Hydroxycinnamates.

BACKGROUND: The structural reinforcement of cell walls by hydroxycinnamates has a significant role in defense against pests and pathogens, but it also interferes with forage digestibility and biofuel production. Elucidation of maize genetic variations that contribute to variation for stem hydroxycinnamate content could simplify breeding for cell wall strengthening by using markers linked to the most favorable genetic variants in marker-assisted selection or genomic selection approaches​. RESULTS: A genome-wide association study was conducted using a subset of 282 inbred lines from a maize diversity panel to identify single nucleotide polymorphisms (SNPs) associated with stem cell wall hydroxycinnamate content. A total of 5, 8, and 2 SNPs were identified as significantly associated to p-coumarate, ferulate, and total diferulate concentrations, respectively in the maize pith. Attending to particular diferulate isomers, 3, 6, 1 and 2 SNPs were related to 8-O-4 diferulate, 5-5 diferulate, 8-5 diferulate and 8-5 linear diferulate contents, respectively. This study has the advantage of being done with direct biochemical determinations instead of using estimates based on Near-infrared spectroscopy (NIRS) predictions. In addition, novel genomic regions involved in hydroxycinnamate content were found, such as those in bins 1.06 (for FA), 4.01 (for PCA and FA), 5.04 (for FA), 8.05 (for PCA), and 10.03 and 3.06 (for DFAT and some dimers). CONCLUSIONS: The effect of individual SNPs significantly associated with stem hydroxycinnamate content was low, explaining a low percentage of total phenotypic variability (7 to 10%). Nevertheless, we spotlighted new genomic regions associated with the accumulation of cell-wall-bound hydroxycinnamic acids in the maize stem, and genes involved in cell wall modulation in response to biotic and abiotic stresses have been proposed as candidate genes for those quantitative trait loci (QTL). In addition, we cannot rule out that uncharacterized genes linked to significant SNPs could be implicated in dimer formation and arobinoxylan feruloylation because genes involved in those processes have been poorly characterized. Overall, genomic selection considering markers distributed throughout the whole genome seems to be a more appropriate breeding strategy than marker-assisted selection focused in markers linked to QTL.

The value of repeat kidney biopsy in quiescent Argentinian lupus nephritis patients.

BACKGROUND: The duration of maintenance therapy after induction therapy for lupus nephritis has not been rigorously established. A common practice is to maintain immunosuppression for 1-2 years after complete remission, and longer for partial remission. The present work addresses whether a repeat kidney biopsy might be informative in deciding who should continue immunosuppression after complete or partial remission. METHODS: The practice in a large Buenos Aires nephrology unit is to repeat a kidney biopsy before finalizing the decision to withdraw or continue immunosuppression. This work reports on a cohort of 25 Hispanic patients that had two or more kidney biopsies, the last occurring after at least 24 months of clinically quiescent disease. RESULTS: Despite normalization of serum creatinine and reduction of proteinuria to <500 mg/d, 30% of patients still had significant activity at the last biopsy. Conversely, 60% of patients with ongoing proteinuria (500-1000 mg/d), or stable but abnormal serum creatinine, had no activity by biopsy. Univariate association analyses demonstrated that improvement in the activity index (AI) of the last biopsy was associated with choice of induction therapy (cyclophosphamide or mycophenolate), improvement in serum creatinine over the first six months of treatment, and improvement in complement component C4. By multivariate regression analyses, two AI prediction models emerged. Cyclophosphamide plus change in serum creatinine or cyclophosphamide plus change in C4 accounted for 50% of the improvement in AI. CONCLUSION: These data suggest that a repeat biopsy may be useful in making the decision to withdraw or continue maintenance immunosuppression.

Identification of single nucleotide polymorphisms (SNPs) for maize cell wall hydroxycinnamates using a multi-parent advanced generation intercross (MAGIC) population.

Higher hydroxycinnamate content makes maize tissues more recalcitrant to damage by insects, less digestible by ruminants, and less suitable for biofuel production. In a Genome Wide Association Analysis (GWAS) study carried out in a maize MAGIC population, we identified 24 SNPs associated with esterified cell wall-bound hydroxycinnamates, that represented 15 Quantitative Traic Loci (QTL). We identified new genomic regions associated to cell wall bound hydroxycinnamates in maize stover that could have an impact on their content across different genetic backgrounds. The high resolution QTL described in this study could be valuable for addressing positional mapping of genes involved in hydroxycinnamate biosynthesis and could uncover genes implicated in the esterification of hydroxycinnamic acids to the arabinoxylan chains that are poorly understood. However, we found that genetic correlation coefficients between hydroxycinnamate content and economical important traits such as saccharification efficiency, animal digestibility andi pest resistance were low to moderate, so modify specific hydroxycinnamates to indirectly improve cultivar performance will be unsuitable.

Association mapping for maize stover yield and saccharification efficiency using a multiparent advanced generation intercross (MAGIC) population.

Cellulosic ethanol derived from fast growing C4 grasses could become an alternative to finite fossil fuels. With the potential to generate a major source of lignocellulosic biomass, maize has gained importance as an outstanding model plant for studying the complex cell wall network and also to optimize crop breeding strategies in bioenergy grasses. A genome-wide association study (GWAS) was conducted using a subset of 408 Recombinant Inbred Lines (RILs) from a Multi-Parent Advanced Generation Intercross (MAGIC) Population in order to identify single nucleotide polymorphisms (SNPs) associated with yield and saccharification efficiency of maize stover. We identified 13 SNPs significantly associated with increased stover yield that corresponded to 13 QTL, and 2 SNPs significantly associated with improved saccharification efficiency, that could be clustered into 2 QTL. We have pointed out the most interesting SNPs to be implemented in breeding programs based on results from analyses of averaged and yearly data. Association mapping in this MAGIC population highlight genomic regions directly linked to traits that influence the final use of maize. Markers linked to these QTL could be used in genomic or marker-assisted selection programs to improve biomass quality for ethanol production. This study opens a possible optimisation path for improving the viability of second-generation biofuels.

Fagerstrom test for nicotine dependence vs heavy smoking index in a general population survey.

BACKGROUND: The Fagerström Test for Nicotine Dependence (FTND) is used for assessing nicotine dependence. A shorter test derived from the FTND used for the general population is the Heavy Smoking Index (HSI) (six questions vs. two). The objective of this study is to compare the validity of the HSI versus the FTND. METHODS: A survey of tobacco use in the general population was carried out in the northern Spanish region of Galicia using both the FTND and the HSI to study a representative sample of 1655 daily smokers. The HSI was compared with the FTND, considered the gold standard. Measures of sensitivity, specificity and predictive values were calculated. Concordance between the tests was also established (Cohen's kappa). RESULTS: Cohen's kappa showed good agreement between measures (Kappa = 0.7); specificity values were also high (Sp = 96.2%). Sensitivity analysis in females (Se = 62.3%) did not show good agreement. CONCLUSIONS: The HSI can be used as a reasonably good screening test in order to identify daily smokers with high nicotine dependence. Nevertheless, for populations or subpopulations having low nicotine dependence, such as women, the FTND is more reliable.

Investigation for a more virulent variant among the c:2b:P1.2,5 Spanish meningococcal epidemic strains by molecular epidemiology.

A rise in the incidence of meningococcal disease has occurred in Spain in recent years, especially in some regions in the north-west of the country. Most cases have been caused by meningococci characterised as Neisseria meningitidis C:2b:P1.2,5. A total of 107 C:2b:P1.2,5 meningococcal isolates (60 from patients and 47 from carriers) and 12 isolates showing related antigenic combinations (C:2b:NST, C:2b:P1.2, C:2b:P1.5, C:NT:P1.2,5) was analysed by pulsed-field gel electrophoresis to determine the genetic variability of the epidemic and related strains. Endonucleases BglII and NheI were used to cut chromosomal DNA. When BglII was used, most of the C:2b:P1.2,5 isolates showed the same pulsotype regardless of whether they were from clinical cases or carriers. Isolates showing the principal profile after digestion with endonuclease BglII were analysed with NheI. Four pulsotypes were identified, of which two were found in only one isolate each. The major profiles (1 and 2) showed differential distribution among clinical and carrier isolates; pulsotype 1 was the most frequent among clinical isolates. However, the proportions of isolates showing profiles 1 and 2 were similar among carrier isolates. This could indicate that there are two variants of the C:2b:P1.2,5 strain with differing pathogenicity.

Impact of meningococcal vaccination with combined serogroups A and C polysaccharide vaccine on carriage of Neisseria meningitidis C.

Two studies of meningococcal carriage state were carried out in Galicia (Spain) before and after a mass vaccination campaign between December 1996 and January 1997 against Neisseria meningitidis serogroup C with meningococcal serogroups A and C polysaccharide vaccine. The studies covered two areas with different incidence rates of meningococcal disease in 1996 (high and low incidence). Carriage rates of serogroup C showed a decrease in both areas, 47 and 65 % respectively, before and after the vaccination. Results showed a decrease in carrier state in the age groups 10-14- and 15-19-year-olds, but not in the 5-9-year-olds. These results demonstrate the effect of immunization on the reduction of the carriage state.

Corneal dioptric power after penetrating keratoplasty.

The dioptric power of the cornea (spherical equivalent) was studied in 60 eyes operated on for penetrating keratoplasty. In order to determine the possible influence of (1) the underlying pathology, (2) the presence of neovascularisation, or (3) the size of the graft the sample was divided into four groups, with the following results: group A (keratoconus, same-sized graft) = 42.25 D; group B (keratoconus, oversized graft) = 45.16 D; group C (keratopathy with minimal or no vascularisation) = 45.34 D; group D (keratopathy with significant vascularisation) = 45.36 D. The results showed that donor-receptor disparity is the main factor determining the outcome of the postoperative corneal spherical power. There was no demonstrable influence from underlying pathology or the presence of vessels in the receptor cornea.

[Analysis of the management of the vaccination campaign in 1996-1997 against meningococcus C in Galicia]. / Análisis de la gestión de la campaña de vacunación 1996-1997 frente al meningococo C en Galicia.

This paper describes the process to design and plan a vaccination campaign against group C N. Meningitidis developed in the Autonomous Community of Galicia between December 9, 1996 and January 31, 1997. We also analyse the results of this process in terms of management results, vaccine coverage and preliminary estimates of effectiveness. A Work group was established, made up of professionals in charge of different intervention areas. A person was designated in charge of the whole campaign and a follow-up and information system was created. The work plan consisted of daily meetings for follow-up, co-ordination and task distribution; and periodical meetings with primary health care and peripheral public health coordinators. Strategies of implantation--in order to make sure the campaign accessibility and acceptability; of budget and of communication with health workers, inhabitants and mass media were developed. Up to 100 tasks were identified to develop the technical information and logistic activities: mailings, meetings, leaflets, ...; purchasing of 584.980 doses of vaccine, supplying to 715 vaccination points (1040 deliveries); problem solving and intervention recording. A vaccination coverage of 85% was achieved, with notification of 8 adverse reactions and 6 errors in the administration of the vaccine (34 children affected). The strategy chosen for the design and planning of the campaign has proven to be effective and valid and sufficient to achieve the final goals, in due time and without problems of misinformation, shortage of vaccine or lack of participation of professionals or people. Mistakes due to incorrect administration of the vaccine, management problems, rupture of the cold chain or recording failures were minimal and accidental.

Fusarium moniliforme keratitis.

We report a case of keratomycosis from which fusarium moniliforme was isolated. After initial therapy without improvement, antifungal testing showed susceptibility to cyclopiroxolamine. After changing to this treatment the infection improved and an eventual healing took place with moderate corneal scarring.

Oral fluorescein angiography and fluoroscopy: determination of plasma fluorescein levels and clinical application.

One hundred oral fluorescein angiographic explorations were performed in 85 patients of both sexes, mean age 55.57 years, and range 8 to 77 years. Fluorescein was administered as one 250-mg (15 patients) or 500-mg (70 patients) capsule per 15 kg of body weight. In 15 fasting and 15 postprandial patients administered 500-mg capsules, no significant differences by group were found between fluorescein plasma levels. Fundus fluorescence under slitlamp illumination was poor for patients receiving the lower dosage of fluorescein, whereas at the higher dosage it was visible in all but one patient. The best filters were found to be a Kodak-Wratten 47A for the excitation filter and Kodak-Wratten 8 for the barrier filter. With a conventional fundus camera and fluorescein angiography filters, good photographs were achieved in all cases. The integrity of the blood-retina barriers was explored for various chorioretinal pathologies.

Heparin inhibits Pseudomonas adherence to soft contact lenses.

Adherence of bacteria to the surface of contact lenses may play an important role in contact lens intolerance and corneal infections. To decrease the capability of bacteria to adhere to contact lenses we incubated two types of soft contact lenses with two strains of Pseudomonas aeruginosa (serotypes 0:11 and 0:8) at a concentration of 5 x 10(7) c.f.u./ml for 12 hours. When heparin was added to the medium at a concentration of 1000 IU/ml the numbers of bacteria adhering to the contact lenses were significantly fewer than in the controls (p < 0.005). Our results suggest that heparin, either included in contact lens solutions or bonded to the surface of the contact lens, may decrease contact-lens-related morbidity.

Carriage of a new epidemic strain of Neisseria meningitidis and its relationship with the incidence of meningococcal disease in Galicia, Spain.

In Galicia, Spain, a dramatic increase in the incidence of meningococcal disease was seen in the 1995-6. The annual incidence rose to 11 per 10(5) inhabitants, and 80% of identified strains were C:2b:P1.2,5. This led to the implementation of an intensive A+C vaccination campaign for the population aged 18 months to 19 years. During this campaign the prevalence of carriage in areas with high and low incidence was studied. Nasopharyngeal swabs were taken from 9796 subjects immediately before the administration of meningococcal vaccine, plated onto Thayer-Martin plates, incubated and sent for analysis to the Reference Laboratory for Neisseria in Spain. The prevalence of the C:2b: P1.2,5 strains was 0.6% (95% CI 0.29-0.88) in the high incidence area, and 0.41% (95 % CI 0.00-1.04) in the low incidence area, and that of serogroup C (all strains) 1.36% (95% CI 0.80-1.80) and 0.89% (95% CI 0.09-1.69) respectively. The prevalence of N. meningitidis (all strains) was almost the same in both areas (8%). Carriers of the epidemic strain were not found in the 2-4 year age group, that most affected by the disease. Our data showed a wide distribution but a low carriage rate of the epidemic strain C:2b:P1.2,5 in the high and low disease incidence areas studied; the difference in the carriage rates between the two areas was not statistically significant.