Disruption of the CFTR gene produces a model of cystic fibrosis in newborn pigs

Almost two decades after CFTR was identified as the gene responsible for cystic fibrosis (CF), we still lack answers to many questions about the pathogenesis of the disease, and it remains incurable. Mice with a disrupted CFTR gene have greatly facilitated CF studies, but the mutant mice do not develop the characteristic manifestations of human CF, including abnormalities of the pancreas, lung, intestine, liver, and other organs. Because pigs share many anatomical and physiological features with humans, we generated pigs with a targeted disruption of both CFTR alleles. Newborn pigs lacking CFTR exhibited defective chloride transport and developed meconium ileus, exocrine pancreatic destruction, and focal biliary cirrhosis, replicating abnormalities seen in newborn humans with CF. The pig model may provide opportunities to address persistent questions about CF pathogenesis and accelerate discovery of strategies for prevention and treatment.     

Expression of the Bcl-2 apoptotic marker in cats diagnosed with inflammatory bowel disease and gastrointestinal lymphoma

Immunolabeling for the critical lymphocyte survival factor, Bcl-2, of intestinal biopsies from cats with histologic evidence of inflammatory bowel disease (IBD) or gastrointestinal (GI) lymphoma was evaluated to determine if expression differed significantly between these two disease processes. Immunolabeling for Bcl-2 was performed on small intestinal endoscopic or full thickness biopsy sections from 55 cats. Diagnosis of IBD, T-cell lymphoma or B-cell lymphoma was established previously. The percentage of infiltrating lymphocytes that were positively labeled for Bcl-2 was subjectively determined for each case. Eight cats were diagnosed with IBD and 47 cats with lymphoma. A significantly higher percentage of cells were positively immunolabeled for Bcl-2 in cats with GI lymphoma [median (range); 90 (5-95)%] compared with cats with IBD [60 (15-95)%] (P = 0.029). However, the overall degree of positive immunolabeling in both groups tended to be high. This over-expression of Bcl-2 may prove useful as a therapeutic target for IBD and GI lymphoma in cats.     

Characterization of Salmonella enterica serovar Typhimurium strains of veterinary origin by molecular typing methods

Twenty-eight strains of Salmonella enterica serovar Typhimurium were characterized by three PCR-based methods. Ten strains harbored type I integrons and two different integron profiles were detected. Typing by amplified fragment length polymorphism (AFLP) resulted in observation of 10 profiles that differed by one to six bands. Salmonella strains were screened for presence of phage genes using a PCR-phage typing; five genes from P22 phage and genes encoding putative virulence factors from phages Gifsy-1, Gifsy-2 and Fels-1 were selected for testing. This set of genes was sufficient for dividing the strains into eight different PCR-phage profiles. Similar grouping of strains was observed in case of all the employed DNA techniques and they corresponded well with the phage type and antimicrobial resistance of the strains. The highest discriminating power was achieved with use of the AFLP, yet the detection of integrons and PCR-phage typing also proved to be valuable in typing the S. Typhimurium strains.     

Modelling crop growth and biomass partitioning to shoots and roots in relation to nitrogen and water availability, using a maximization principle. II. Simulation of crop nitrogen balance

This study analysed of the ability of a crop model to simulate crop nitrogen (N) balance. The model was originally developed to serve as a foundation to develop a decision-making tool to analyse the impact of water management and nitrogen fertilization on crop yield. The model included a dynamic parameter for allocation of dry matter between root and shoot allowing root to shoot ratio to vary according to differing environmental conditions. The new allocation parameter was introduced in order to make the model more applicable under water and nitrogen limited growing conditions. Two wheat (Triticum aestivum L.) data sets were used to test the model simulations. Generally, the model simulations agreed well with the recorded data on crop N uptake. The relationship between the actual and simulated amount of N taken up by the crop was close in the calibration treatments of a greenhouse experiment. The coefficient of determination (r²) of the regression line (simulated value = independent variable, measured value = dependent variable) was 0.90. The r² was 0.83 for the validation data. In the field experiments, the r² values were 0.91 for the calibration data and 0.82 for the validation data. In field data, the model underestimated in some cases the crop N uptake during the period when actual shoot dry weight increased exponentially in spring. Therefore, methods used in computation of nitrogen uptake have to be analysed further. Plant organ N content was simulated satisfactorily for both greenhouse and field data. However, the range over which the simulated values varied was larger than in the actual data.

The results from the study indicate that our model is capable of simulating the crop N balance and we suggest that the model could be used when developing an N application decision tool for field crops. However, the availability of N and soil water were provided as inputs in the present study. Thus, the model should be integrated with models simulating below ground processes in the future. Moreover, the model should be further validated with actual field data.     

Post-harvest disorders and mineral composition of apple fruits as affected by pre-harvest calcium treatments

Abstract

The effect of pre-harvest calcium sprays, CaCl₂ and Ca (NO₃)_2, on apple (Malus domestica) N, P, K, Ca and Mg content, storability and incidence of physiological disorders (superficial scald, bitter pit, physiological spot) was studied using two cultivars, ‘Krameri Tuviõun’ and ‘Talvenauding’. In the first year calcium treatment did not reduce any physiological disorders or loss of marketable yield. In the second year calcium treatment reduced storage losses until four months after storage. Bitter pit in ‘Krameri Tuviõun’ was unaffected by calcium treatment, but physiological spot of ‘Krameri Tuviõun’ and superficial scald of ‘Talvenauding’ were reduced by calcium treatment in the second year. Both physiological disorders of 'Krameri Tuviõun’ correlated negatively with Mg and P content and Mg/Ca ratio in apples. Superficial scald of ‘Talvenauding’ correlated negatively with Ca content and positively with K/Ca ratio, N/Ca ratio and Mg/Ca ratio in fruits. The conclusion can be made that content of Ca and its ratios with other nutrients plays an important role in the development of superficial scald on ‘Talvenauding’ fruits, and increasing Ca content in fruit can therefore be recommended for improving post-harvest quality of this cultivar. Since bitter pit in 'Krameri Tuviõun’ was not reduced by calcium treatment, it would be worth trying other measures for this cultivar.     

Exploring the population genetics of genebank and historical landrace varieties

Landrace accessions have long been recognized as an important source of genetic diversity for crop species, and landraces are stored in genebanks across the world as genetic resources for future crop development. Landraces are also an important part of the human cultural heritage and as such they have been used for genetic studies to make inferences about historical agriculture. However, surprisingly little is known about the within-accession diversity of landrace crops of different species. In order to evaluate the diversity of Swedish landraces we used microsatellite markers to genotype accessions of four species (barley, pea, oats and rye), both extant genebank material and 114-year-old seed samples of similar geographic origin and type. We found consistently high levels of within-population genetic diversity in the historical material, but varying and often lower diversity levels in the genebank accessions. We also make tentative conclusions about how representative the genebank material is to what was originally cultivated in its reported area of origin and suggest that the true identity of the genebank accessions is unclear and that historical seed collections should be a more appropriate material for the study of historical agriculture.     

Temperature sum accumulation effects on within-population variation and long-term trends in date of bud burst of European white birch (Betula pendula)

Within-population variation in phenology of boreal trees indicates their adaptability to climatic variations. Although interannual variations in date of bud burst have been widely discussed, little is known about within-population variation, the key determinants for this variation and the effects of this variation on estimates of trends in bud burst date. Over a period of nine years, we monitored timing of bud burst daily in 30 mature white birch (Betula pendula Roth) trees in a naturally regenerated stand. Our results revealed not only large interannual variation but also considerable intraannual variation among individual trees in date of bud burst, the maximum within-population variation being four weeks. Bud burst can be accurately predicted by the date when a threshold value of temperature sum in spring is reached (base temperature +5 degrees C). Based on this temperature sum and past temperature records, we estimated the trend in date of bud burst. The linear trend estimate based on the years 1926-2005 is an advancement of 1.2 days per decade (95% confidence interval, +/- 0.7 days), which is much less than that predicted by time series based on coarser time intervals. We conclude that, because of large interannual differences, and large annual within-population variations in bud burst, estimates of bud burst date based on measurements made over a period of only a few decades are unreliable.     

Predicting and calibrating diameter distributions of Eucalyptus grandis (Hill) Maiden plantations in Zimbabwe

Diameter distribution models for even-aged Eucalyptus grandis plantations in Zimbabwe were developed using the two-parameter Weibull function. The analysis was based on data from Correlated Curve Trend (CCT) experiments replicated on four different sites. Parameters of the Weibull distribution were predicted using stand characteristics as regressors. Two sets of parameter models were estimated: a set with and one without stand basal area as a predictor. Stand variables such as dominant height, age, site index and number of stems were used in both sets. The models were further calibrated to result in a given number of stems and stand basal area simultaneously. The usability of constructed models was tested both in prediction of yield in a stand inventory situation and in simulation of growth in connection with different growth models. The results indicated that models not including stand basal area produce considerably less precise stand volume estimates compared to models including also stand basal area. Calibration improved the accuracy of diameter distribution models. In growth simulation diameter distribution models can be connected both to single tree growth models and to stand projection models. The usability of calibration in growth simulation depends on the accuracy of the prediction of stand characteristics.