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Selenium-enriched yeast possesses the unique ability of transforming chemical selenium, such as sodium selenite, into a biologically active form, which mitigates its toxic effects on the human body. The transformation product of this process, selenomethionine, can be safely and effectively absorbed and utilized by the human body; hence, it has been spiked into a selenium-enriched supplement. This study employs two distinct measurement strategies to determine the selenomethionine content in two candidate reference materials, a selenium-enriched yeast powder and supplement, using both organic and inorganic mass spectrometry. The concentrations of selenomethionine in the selenium-enriched yeast were determined using HPLC-ICP-MS and HPLC- ESI-MS/MS, with mass fractions measured at 718 mg SeMet kg−1 and 715 mg SeMet kg−1, respectively. Notably, both methods yielded consistent results for the selenium supplement, with a selenomethionine mass fraction of 59 mg SeMet kg−1. Ultimately, the certified values of these candidate reference materials were determined as 716 mg kg−1 and 59 mg SeMet kg−1 with expanded uncertainties of 36 mg SeMet kg−1 (k = 2) and 5 mg SeMet kg−1 (k = 2), respectively. The development of these candidate reference materials serves as a valuable reference for diverse methods aiming to determine the value of organic selenium speciation in complex food substrates.

Abstract Background Patients with primary hyperparathyroidism (PHPT) may be asymptomatic, and some may present with normocalcemic PHPT (NPHPT). Patients with vitamin D deficiency may also be asymptomatic, with normal calcium and elevated PTH concentrations. These latter patients are usually diagnosed with vitamin D deficiency-induced secondary hyperparathyroidism (VD-SHPT). Therefore, it is very difficult to distinguish PHPT and NPHPT from VD-SHPT based on calcium or PTH concentrations in clinical settings. In this case-control study, we aimed to verify the diagnostic power of a new parathyroid function index (PFindex = Ca*PTH/P). Methods This study enrolled 128 patients with surgically and pathologically confirmed PHPT, including 36 with NPHPT, at a hospital in West China between January 2009 and September 2017. Thirty-seven patients with VD-SHPT and 45 healthy controls were selected from the population of a cross-sectional epidemiological study as the SHPT and healthy groups, respectively. We used the PFindex to describe the characteristics of PHPT, NPHPT, and VD-SHPT.. Differences between the four groups were compared, and a receiver operating characteristic (ROC) curve analysis was used to evaluate the diagnostic power of PFindex. Results The PHPT group had the highest PFindex (454 ± 430), compared to the other three groups (NPHPT: 101 ± 111; SHPT: 21.7 ± 6.38; healthy: 12.2 ± 2.98, all p 34 to differentiate NPHPT from VD-SHPT yielded the highest positive likelihood ratio and lowest negative likelihood ratio. Conclusion The PFindex provided excellent diagnostic power for the differentiation of NPHPT from VD-SHPT. This simple tool may be useful for guiding timely decision-making processes regarding the initiation of vitamin D treatment or surgery for PHPT.

Background As the largest low-latitude permafrost region, the Tibetan Plateau (TP) is an important part of the earth's terrestrial ecosystem and one of the most vulnerable areas to climate change and human activities. However, to the best of our knowledge, the bacterial communities in TP soils and their roles in biogeochemical cycles remain limited. Results In this study, we report the bacterial community structure and function as well as their correlation with environmental factors in TP major ecosystems (farmland, alpine meadow and oligosaline lake) by using metagenomic approaches. Compared with other soil samples in various environments, TP soils share a core set of microorganisms with a distinct abundance and composition. Among TP soil samples, the taxonomic and functional composition of bacterial communities among the upper (3-5 cm) and lower (18-20 cm) soils of farmland sites were highly similar, whereas the dissimilarities within alpine meadow samples were significantly greater than among farmland samples. A similar pattern was observed in elements cycles and pathways associated with adaption to environment and land use types. Canonical correlation analysis revealed that the bacterial communities in most of farmland and alpine meadow soil samples were also significantly correlated with geogenic variables. Specifically, the root-nodule bacteria are negatively correlated with the soil moisture and pH, while Thiobacillus associated with sulfur cycles show potential responses to low temperature and intense UV radiation. Conclusions These findings indicate that the bacterial community structure and functions in TP soils were influenced by both human activities and soil environmental properties, and that the bacterial communities appeared to be more homogenized in the farmland soils compared with pristine alpine meadows. [ABSTRACT FROM AUTHOR]

sediment core collected from coastal zone near the Qiao Island in the Pearl River Estuary was analyzed for total metal concentrations, chemical partitioning, and physico-chemical properties. Three vertical distribution patterns of the heavy metals in the sediment core were identified, respectively. The dominant binding phases for Cu, Pb, Cr, and Zn were the residual and Fe/Mn oxides fractions. Cd in all sediments was mainly associated with exchangeable fraction. Influences of total organic carbon content and cation exchange capacity on the total concentrations and fractions of almost all the metals were not evident, whereas sand content might play an important role in the distributions of residual phases of Cr, Cu, Pb, and Zn. In addition, sediment pH had also an important influence on the Fe/Mn oxides, organic/sulfide and residual fractions of Cr, Cu, and Zn. Contamination assessment on the heavy metals in the sediment core adopting Index of Geoaccumulation showed that Cr, V, Be, Se, Sn, and Tl were unpolluted, while Cu, Ni, Pb, Zn, Cd, and Co were polluted in different degrees throughout the core. It was remarkable that the various pollution levels of the metals from moderate (for Cu, Pb, and Zn) to strong (for Cd) were observed in the top 45 cm of the profiles. The relative decrease of the residual fraction in the upper 45 cm of the core is striking, especially for Zn and Cu, and, also for Pb, and Cr. The change in fraction distribution in the upper 45 cm, which is very much contrasting to the one at larger depths, confirms that the residual fraction is related to the natural origin of these metals, whereas in the upper part, the non-residual fractions (mainly the Fe/Mn oxides fraction) are increased due to pollution in the last decade. The possible sources for Cu, Pb, Zn, and Cd contaminations were attributed to the increasing municipal and industrial wastewater discharges, agricultural runoff, atmospheric inputs, and runoff from upstream mining or smelting activities, which may be associated with an accelerating growth of economy in the Pearl River Delta region in the past decade. [ABSTRACT FROM AUTHOR]

Abiotic stresses such as drought and extremes of temperature commonly reduce both yield and quality of potato. This study investigated the potential to use gene transfer technology to enhance the tolerance of potato to commonly encountered abiotic stresses. Agrobacterium mediated transformation was used to create lines of potato (cv. Desiree) that over-expressed either a wheat mitochondrial Mn superoxide dismutase (SOD3:1), dehydrin 4 (DHN 4) isolated from barley, a cold-inducible transcriptional factor DREB/CBF1 isolated from canola or ROB5, a stress inducible gene isolated from bromegrass that encodes for a heat stable LEA group 3-like protein. The transgenes were under the control of either a constitutive 35S promoter or a stress-induced Arabidopsis COR78 promoter. Yield potential of the transformed lines was evaluated under drought stress conditions in a greenhouse trial and under non-irrigated conditions in field trials conducted over 4 years in Saskatoon, Saskatchewan. In the years when the field trials experienced significant drought stress (2001, 2003 and 2006) many of the transformed lines produced higher yields than the control. However, under relatively cooler, wetter conditions (2005 cropping season) yields of most transformed lines were equivalent or inferior to the non-transformed parental line. Under non-stressed conditions, transformations utilizing the stress-induced COR78 promoter were higher yielding than transformations based on the constitutive 35S promoter. Combining the ROB5, DHN or SOD3.1 transgenes with the COR78 promoter all showed significant potential to enhance yields under moisture stress. All of the transgenes appeared to enhance the heat stress tolerance (44°C) of whole plants or excised leaves, with lines transformed with SOD3.1 showing the greatest effect. In low temperature stress trials conducted under controlled environment conditions and in the field, lines over-expressing SOD3:1 showed an enhanced capacity to grow at sub-optimal temperatures (10°C), while lines transformed with SOD3.1 or ROB5 had greater tolerance of freezing temperatures than the parental line. These results are encouraging as even a small degree of enhancement of stress tolerance has the potential to produce significant economic benefits in high value/stress sensitive crops such as potato. [ABSTRACT FROM AUTHOR]

The objective of this study was to evaluate the performance of transgenic canola ( Brassica napus) plants over-expressing a wheat mitochondrial Mn superoxide dismutase (Mn SOD3.1) subjected to environmental stresses in the field and in controlled environments. Mn SOD3.1 was regulated by either CaMV 35S or Arabidopsis COR78 promoters. RT-PCR and a SOD enzyme activity assays demonstrated Mn SOD3.1 was expressed at both the mRNA and protein levels. Enzyme activity assays exhibited total SOD activity was up to 41.8% and up to 26.7% higher in the 35S:SOD3.1 and in the COR78:SOD3.1 transgenic plants than in the control, respectively. Germination studies, conducted at suboptimal (8°C) and optimal (23°C) temperatures, identified transgenic lines that germinated earlier than the control. In the field under drought conditions, several transgenic lines emerged earlier than the control. In both greenhouse and field environments, several transgenic lines were significantly taller than the control and over 50% of the transgenic canola lines flowered 7–14 days earlier than the control. Over expression of Mn SOD3.1 enhanced heat, drought and cold tolerance both in the field and under artificial stress conditions. This is one of the first tests conducted on transgenic canola plants subjected to field conditions. [ABSTRACT FROM AUTHOR]

Several Daucus carota (carrot) and Nicotiana tabacum (tobacco) cell lines that had been selected as resistant to Pro, Trp, Lys and Met analogs were thawed after over 10 years of cryostorage in liquid nitrogen. Some of these cell lines had been cloned. Viable cells were recovered in all cases, and growing lines were recovered from the carrot lines when placed either on feeder plates or directly into liquid medium. Some tobacco cultures were recovered only in liquid medium, but two Trp analog-resistant cloned lines could not be recovered after several attempts. Generally the cryopreserved lines retained the original resistance and corresponding free amino acid levels while the same lines maintained as callus with monthly transfers for the same period often lost the resistance. Our study shows that carrot and some, but not all, tobacco cultured cell lines can be cryopreserved for over 10 years and still be recovered with their original characteristics. [ABSTRACT FROM AUTHOR]