The role of selenium in thyroid hormone metabolism and effects of selenium deficiency on thyroid hormone and iodine metabolism

Selenium deficiency impairs thyroid hormone metabolism by inhibiting the synthesis and activity of the iodothyronine deiodinases, which convert thyroxine (T₄) to the more metabolically active 3,3′-5 triiodothyronine (T₃). Hepatic type I iodothyronine deiodinase, identified in partially purified cell fractions using affinity labeling with [¹²⁵I]N-bromoacetyl reverse triiodothyronine, is also labeled with⁷⁵Se by in vivo treatment of rats with⁷⁵Se-Na₂SeO₃. Thus, the type I iodothyronine 5′-deiodinase is a selenoenzyme. In rats, concurrent selenium and iodine deficiency produces greater increases in thyroid weight and plasma thyrotrophin than iodine deficiency alone. These results indicate that a concurrent selenium deficiency could be a major determinant of the severity of iodine deficiency.     

Fluorescence detected magnetic resonance of the primary donor and inner core antenna chlorophyll in Photosystem I reaction centre protein: Sign inversion and energy transfer

The Photosystem I reaction centre protein CP1, isolated from barley using polyacrylamide gel electrophoresis showed an EPR (Electron Paramgnetic Resonance) spectrum with the polarisation pattern AEEAAE, typical of the primary donor triplet state ³P700, created via radical pair formation and recombination. ³P700 could also be detected by Fluorescence Detected Magnetic Resonance (FDMR) at _f > 700 nm even in the presence of a large number of chlorophyll antennae. Its zero field splitting parameters, D=282.5×10^-4 cm^-1 and E=38.5×10^-4 cm^-1, were independent of the detection wavelength, and agreed with ADMR (Absorption Detected Magnetic Resonance) and EPR values. The signs of the ³P700 D+E and D-E transitions were positive (increase in fluorescence intensity on applying a resonance microwave field). In contrast, in the emission band 685 < _f < 700 nm FDMR spectra with negative D+E and D-E transitions were detected, and the D value was wavelength-dependent. These FDMR results support an excitation energy transfer model for CP1, derived from time-resolved fluorescence studies, in which two chlorophyll antenna forms are distinguished, with fluorescence at 685 < _f < 700 nm (inner core antennae, F690), and _f > 700 nm (low energy antenna sites, F720), in addition to the P700. The FDMR spectrum in F690 emission can be interpreted as that of ³P700, observed via reverse singlet excitation energy transfer and added to the FDMR spectrum of the antenna triplet states generated via intramolecular intersystem crossing. This would indicate that reversible energy transfer between F690 and P700 occurs even at 4.2 K.Abbreviations Chl chlorophyll - CP1 core chlorophyll protein of Photosystem I - EPR electron paramagnetic resonance - F690, F720 chlorophyll forms having fluorescence maximum at 690–695 and 720 nm, respectively - F(A)(O)DMR fluorescence (absorption) (optical) detected magnetic resonance - FF fluorescence fading - ISC intramolecular intersystem crossing - _f fluorescence emission wave-length - LHC I light harvesting chlorophyll a/b protein of Photosystem I - P700 primary donor of Photosystem I - PS I Photosystem I - RC reaction centre - RP radical pair - SDS sodium dodecyl sulphate - ZFS zero field splitting     

A comparative study of allergenic and potentially allergenic enzymes fromDermatophagoides pteronyssinus,D. farinae andEuroglyphus maynei

The presence of the enzymatically active allergens equivalent toDer p I (cysteine protease),Der p III (serine protease) and amylase in extracts ofDermatophagoides pteronyssinus, D. farinae andEuroglyphus maynei was determined using appropriate enzymatic techniques. Biochemical equivalents of all three allergens were present in each extract studied. Studies also showed that the mite extracts contained a variety of other biochemically active enzymes including trypsin, chymotrypsin, carboxypeptidase A and B, glucoamylase and lysozyme. Marked differences in the relative concentrations of some of these enzymes in different mite extracts were observed, particularly trypsin and carboxypeptidase A. The enzymes were physicochemically similar to equivalent enzymes from vertebrate and invertebrate sources. Chromatofocusing studies of faecal extracts derived fromD. pteronyssinus andD. farinae showed that several isoforms of each enzyme were present. The data indicated that there were more trypsin isoforms, with pI over a wider range, in extracts prepared fromD. pteronyssinus. Proteases and carbohydrases were also found in extracts prepared from faecally enriched material suggesting that they were endoperitrophic and associated with mite digestion. The data suggest that not only are the group I, III and amylase allergens a consistent feature of most pyroglyphid dust mites but also that other proteases and carbohydrases present in mite faeces are allergenic.     

Expression of P2X1 receptors in somatostatin-containing cells in mouse gastrointestinal tract and pancreatic islets of both mouse and human

With immunohistochemical and Western blot techniques, P2X1 receptors were detected in the whole mouse gastrointestinal tract and pancreatic islets of mouse and human. (1) δ Cells containing somatostatin (SOM) in the stomach corpus, small intestines, distal colon, pancreatic islets of both mouse and human express P2X1 receptors; (2) strong immunofluorescence of P2X1 receptors was detected in smooth muscle fibers and capillary networks of the villus core of mouse intestine; and (3) P2X1 receptor-immunoreactive neurons were also detected widely in both mouse myenteric and submucosal plexuses, all of which express SOM. The present data implies that ATP via P2X1 receptors is involved in SOM release from pancreatic δ cells, enteric neurons, and capillary networks in villi.     

Band‐like Charge Photogeneration at a Crystalline Organic Donor/Acceptor Interface

Organic photovoltaic cells possess desirable practical characteristics, such as the potential for low‐cost fabrication on flexible substrates, but they lag behind their inorganic counterparts in performance due in part to fundamental energy loss mechanisms, such as overcoming the charge transfer (CT) state binding energy when photogenerated charge is transferred across the donor/acceptor interface. However, recent work has suggested that crystalline interfaces can reduce this binding energy due to enhanced CT state delocalization. Solar cells based on rubrene and C₆₀ are investigated as an archetypal system because it allows the degree of crystallinity to be moldulated from a highly disordered to highly ordered system. Using a postdeposition annealing method to transform as‐deposited amorphous rubrene thin films into ones that are highly crystalline, it is shown that the CT state of a highly crystalline rubrene/C₆₀ heterojunction undergoes extreme delocalization parallel to the interface leading to a band‐like state that exhibits a linear Stark effect. This state parallels the direct charge formation of inorganic solar cells and reduces energetic losses by 220 meV compared with 12 other archetypal heterojunctions reported in the literature.     

Diet acceptance and preference of the edible grasshopper <Emphasis Type="Italic">Ruspolia differens</Emphasis> (Orthoptera: Tettigoniidae)

The edible grasshopper Ruspolia differens (Orthoptera: Tettigoniidae) gathered seasonally from the wild is a highly valued and an economically important edible insect, particularly in East Africa. To reduce the pressure on wild populations, a sustainable mass production technique needs to be developed. Unfortunately, however, basic biological know-how on feeding habits of R. differens is poorly understood, which poses a constraint on the development of mass-rearing technology. Here, we evaluated the acceptance and feeding preference of R. differens for 16 cultivated or processed foods using no-choice and multiple-choice laboratory bioassays. The results indicated that adult R. differens can eat a wide variety of foods but does not necessarily accept all the foods equally. Furthermore, our experiments showed that R. differens has high ability to select diet among those available. The order of decreasing preference was wheat bran > germinated finger millet > rice seed head > finger millet seed head > chicken feed egg booster > sorghum seed head. Finally, our study indicated that sex and color morph are not associated with the order of acceptance and preference of diets in R. differens. These results show potential foods that could be utilized for developing future mass-rearing methods for R. differens.     

Biodegradability of polar compounds formed from weathered diesel

Once released into the environment, petroleum is exposed to biological and physical weathering processes which can lead to the formation and accumulation of highly recalcitrant polar compounds. These polar compounds are often challenging to analyse and can be present as an “unresolved complex mixture” (UCM) in total petroleum hydrocarbon (TPH) analyses and can be mistaken for natural organic matter. Existing research on UCMs comprised of polar compounds is limited, with a majority of the compounds remaining unidentified and their long-term persistence unknown. Here, we investigated the potential biodegradation of these recalcitrant polar compounds isolated from weathered diesel contaminant, and the changes in the microbial community composition associated with the biodegradation process. Microcosms were used to study the biodegradability of the polar compounds under various aerobic and anaerobic conditions and the results compared against the biodegradation of fresh diesel. Under all conditions tested, the majority of the polar UCM contaminant remained recalcitrant to biodegradation. The degradation was limited to the TPH portion of the polar UCM, which represented a minor fraction of the total polar UCM concentration. Changes in microbial community composition were observed under different redox conditions and in the presence of different contaminants. This work furthers the understanding of the biodegradation and long-term recalcitrance of polar compounds formed through weathering at contaminated legacy sites.     

Overview,opportunities and outlook for Australian spiny lobster fisheries

Australia’s lobster fisheries are relatively small in volume (9500t) compared with global production (289,000t), but are the country’s most valuable in terms of both overall production and value of export (2014 Gross Value of Production of $610 million AUD). Further, they support commercial, recreational and indigenous fishers along most of the continent’s coastline. Here we review similarities and key differences between these lobster fisheries, based on biological characteristics, fishery data collection, assessment and management methods, and supply chain considerations. A diverse range of palinurid lobsters occur in Australia, but only three genera, distributed across eight different management jurisdictions, support significant fisheries. Catches of western rock lobster Panulirus cygnus dominate landings (61%), followed by southern rock lobster Jasus edwardsii, tropical lobster Panulirus ornatus and the eastern rock lobster Sagmariasus verreauxi. Large-scale environmental influences such as climate change are impacting on these fisheries in similar or different ways forcing new management and raising the need for greater resilience in current supply chains. Although these are separate fisheries, the integrated nature of the dominant Chinese export markets suggests potentially important economic and market-related interactions. Our overview highlights the critical role of continued monitoring of recruitment pulses, in combination with robust harvest strategies, to ensure that harvests respond adequately and fisheries achieve biological and economic sustainability. Approaches that also include socio-cultural considerations (triple bottom line) are important given many fisheries include indigenous Australians. Our integrated analysis of Australian lobster fisheries highlights differences and similarities with spiny lobster fisheries worldwide and lessons from opportunities, including adapting to new free trade agreements, enhancing the reputation of wild lobsters as a whole, sharing expertise, and better alignment of supply and demand.