Physiological responses of plants to in vivo X-ray damage from X-ray fluorescence measurements: insights from anatomical, elemental, histochemical, and ultrastructural analyses.

X-ray fluorescence spectroscopy (XRF) is a powerful technique for the in vivo assessment of plant tissues. However, the potential X-ray exposure damages might affect the structure and elemental composition of living plant tissues, leading to artefacts in the recorded data. Herein, we exposed in vivo soybean (Glycine max (L.) Merrill) leaves to several X-ray doses through a polychromatic benchtop microprobe X-ray fluorescence spectrometer, modulating the photon flux density by adjusting either the beam size, current, or exposure time. Changes in the irradiated plant tissues' structure, ultrastructure, and physiology were investigated through light and transmission electron microscopy (TEM). Depending on X-ray exposure dose, decreased K and X-ray scattering intensities and increased Ca, P, and Mn signals on soybean leaves were recorded. Anatomical analysis indicated the necrosis of epidermal and mesophyll cells on the irradiated spots, where TEM images revealed the collapse of cytoplasm and cell wall breaking. Furthermore, the histochemical analysis detected the production of reactive oxygen species and the inhibition of chlorophyll autofluorescence in these areas. Under certain X-ray exposure conditions, e.g. high photon flux density and long exposure time, XRF measurements may affect the soybean leaves structures, elemental composition, and cellular ultrastructure, inducing programmed cell death. Our characterization shed light on the plant's responses to the X-ray-induced radiation damage and might help to establish proper X-ray radiation limits and novel strategies for in vivo benchtop-XRF analysis of vegetal materials.

Population genetic structure of the maize weevil, Sitophilus zeamais, in southern Mexico.

The maize weevil, Sitophilus zeamais, is a ubiquitous pest of maize and other cereal crops worldwide and remains a threat to food security in subsistence communities. Few population genetic studies have been conducted on the maize weevil, but those that exist have shown that there is very little genetic differentiation between geographically dispersed populations and that it is likely the species has experienced a recent range expansion within the last few hundred years. While the previous studies found little genetic structure, they relied primarily on mitochondrial and nuclear microsatellite markers for their analyses. It is possible that more fine-scaled population genetic structure exists due to local adaptation, the biological limits of natural species dispersal, and the isolated nature of subsistence farming communities. In contrast to previous studies, here, we utilized genome-wide single nucleotide polymorphism data to evaluate the genetic population structure of the maize weevil from the southern and coastal Mexican states of Oaxaca and Chiapas. We employed strict SNP filtering to manage large next generation sequencing lane effects and this study is the first to find fine-scale genetic population structure in the maize weevil. Here, we show that although there continues to be gene flow between populations of maize weevil, that fine-scale genetic structure exists. It is possible that this structure is shaped by local adaptation of the insects, the movement and trade of maize by humans in the region, geographic barriers to gene flow, or a combination of these factors.

Comparison of agarose gel and capillary zone electrophoresis methods with preliminary reference interval generation using capillary zone electrophoresis in bald eagles (Haliaeetus leucocephalus).

BACKGROUND: Electrophoresis can be used to aid in the diagnosis of different diseases in avian species. Capillary zone electrophoresis (CZE) is an automated method that is proposed to be superior to the dye methods used in agarose gel electrophoresis (AGE). However, reference intervals (RIs) for CZE in avian species and comparison studies between electrophoretic methods are lacking. OBJECTIVES: The goals of the current study were to compare AGE and CZE methods and determine reference intervals for CZE using plasma from bald eagles (Haliaeetus leucocephalus). METHODS: Heparinized plasma samples from 44 bald eagles (mean age 18.7 years) under managed care were examined by AGE and CZE. Method comparison analyses were completed, as well as the generation of preliminary RIs using the CZE method and ASVCP guidelines. RESULTS: Passing-Bablok regression and Bland-Altman plots demonstrate that these methods are not equivalent. All fractions were significantly correlated between the methods except for alpha 1 globulin. Inter-assay and intra-assay CVs for CZE were lower or comparable to AGE and ranged from 2.4% to 15.4%, and 0.8% to 8.3%, respectively. CZE resolved more fractions than AGE with two fractions observed in the beta and gamma region vs one for AGE in each region. CONCLUSIONS: CZE provided improved resolution and reproducibility for the quantitation of protein fractions in the bald eagle. Although most fraction results correlated with AGE, these methods were judged as not equivalent, necessitating method-specific Rls. Reference intervals generated from a limited number of mostly aged individuals under managed care should be considered preliminary; additional studies will aid in the production of more robust intervals.

Efficacy and safety of colesevelam in patients with type 2 diabetes mellitus and inadequate glycemic control receiving insulin-based therapy.

BACKGROUND: Poor glycemic control is a risk factor for microvascular complications in patients with type 2 diabetes mellitus. Achieving glycemic control safely with insulin therapy can be challenging. METHODS: A prospective, 16-week, multicenter, randomized, double-blind, placebo-controlled, parallel-group study conducted at 50 sites in the United States and 1 site in Mexico between August 12, 2004, and December 28, 2005. Subjects had type 2 diabetes mellitus that was not adequately controlled (glycated hemoglobin level, 7.5%-9.5%, inclusive) receiving insulin therapy alone or in combination with oral antidiabetes agents. In total 287 subjects (52% men; mean age, 57 years; with a mean baseline glycated hemoglobin level of 8.3%) were randomized: 147 to receive colesevelam hydrochloride, 3.75 g/d, and 140 to receive placebo. RESULTS: Using the least squares method, the mean (SE) change in glycated hemoglobin level from baseline to week 16 was -0.41% (0.07%) for the colesevelam-treated group and 0.09% (0.07%) for the placebo group (treatment difference, -0.50% [0.09%]; 95% confidence interval, -0.68% to -0.32%; P < .001). Consistent reductions in fasting plasma glucose and fructosamine levels, glycemic-control response rate, and lipid control measures were observed with colesevelam. As expected, the colesevelam-treated group had a 12.8% reduction in low-density lipoprotein cholesterol concentration relative to placebo (P < .001). Of recipients of colesevelam and placebo, respectively, 30 and 26 discontinued the study prematurely; 7 and 9 withdrew because of protocol-specified hyperglycemia, and 10 and 4 withdrew because of adverse events. Both treatments were generally well tolerated. CONCLUSIONS: Colesevelam treatment seems to be safe and effective for improving glycemic control and lipid management in patients with type 2 diabetes mellitus receiving insulin-based therapy, and it may provide a novel treatment for improving dual cardiovascular risk factors.