Partial ablation of adult Drosophila insulin-producing neurons modulates glucose homeostasis and extends life span without insulin resistance

In Drosophila melanogaster (D. melanogaster), neurosecretory insulin-like peptide-producing cells (IPCs), analogous to mammalian pancreatic β cells are involved in glucose homeostasis. Extending those findings, we have developed in the adult fly an oral glucose tolerance test and demonstrated that IPCs indeed are responsible for executing an acute glucose clearance response. To further develop D. melanogaster as a relevant system for studying age-associated metabolic disorders, we set out to determine the impact of adult-specific partial ablation of IPCs (IPC knockdown) on insulin-like peptide (ILP) action, metabolic outcomes and longevity. Interestingly, while IPC knockdown flies are hyperglycemic and glucose intolerant, these flies remain insulin sensitive as measured by peripheral glucose disposal upon insulin injection and serine phosphorylation of a key insulin-signaling molecule, Akt. Significant increases in stored glycogen and triglyceride levels as well as an elevated level of circulating lipid measured in adult IPC knockdown flies suggest profound modulation in energy metabolism. Additional physiological outcomes measured in those flies include increased resistance to starvation and impaired female fecundity. Finally, increased life span and decreased mortality rates measured in IPC knockdown flies demonstrate that it is possible to modulate ILP action in adult flies to achieve life span extension without insulin resistance. Taken together, we have established and validated an invertebrate genetic system to further investigate insulin action, metabolic homeostasis and regulation of aging regulated by adult IPCs.Key words: Drosophila melanogaster, insulin-producing cells (IPCs), drosophila insulin-like peptides (DILPs), type 2 diabetes, oral glucose tolerance test (OGTT), insulin sensitivity, energy metabolism, life span     

Consequences of daily administered parathyroid hormone on myeloma growth, bone disease, and molecular profiling of whole myelomatous bone

Background

Induction of osteolytic bone lesions in multiple myeloma is caused by an uncoupling of osteoclastic bone resorption and osteoblastic bone formation. Current management of myeloma bone disease is limited to the use of antiresorptive agents such as bisphosphonates.

Methodology/Principal Findings

We tested the effects of daily administered parathyroid hormone (PTH) on bone disease and myeloma growth, and we investigated molecular mechanisms by analyzing gene expression profiles of unique myeloma cell lines and primary myeloma cells engrafted in SCID-rab and SCID-hu mouse models. PTH resulted in increased bone mineral density of myelomatous bones and reduced tumor burden, which reflected the dependence of primary myeloma cells on the bone marrow microenvironment. Treatment with PTH also increased bone mineral density of uninvolved murine bones in myelomatous hosts and bone mineral density of implanted human bones in nonmyelomatous hosts. In myelomatous bone, PTH markedly increased the number of osteoblasts and bone-formation parameters, and the number of osteoclasts was unaffected or moderately reduced. Pretreatment with PTH before injecting myeloma cells increased bone mineral density of the implanted bone and delayed tumor progression. Human global gene expression profiling of myelomatous bones from SCID-hu mice treated with PTH or saline revealed activation of multiple distinct pathways involved in bone formation and coupling; involvement of Wnt signaling was prominent. Treatment with PTH also downregulated markers typically expressed by osteoclasts and myeloma cells, and altered expression of genes that control oxidative stress and inflammation. PTH receptors were not expressed by myeloma cells, and PTH had no effect on myeloma cell growth in vitro.

Conclusions/Significance

We conclude that PTH-induced bone formation in myelomatous bones is mediated by activation of multiple signaling pathways involved in osteoblastogenesis and attenuated bone resorption and myeloma growth; mechanisms involve increased osteoblast production of anti-myeloma factors and minimized myeloma induction of inflammatory conditions.     

Proteome analysis of soybean roots subjected to short-term drought stress

Drought is one of the most important constraints on the growth and productivity of many crops, including soybeans. However, as a primary sensing organ, the plant root response to drought has not been well documented at the proteomic level. In the present study, we carried out a proteome analysis in combination with physiological analyses of soybean roots subjected to severe but recoverable drought stress at the seedling stage. Drought stress resulted in the increased accumulation of reactive oxygen species and subsequent lipid peroxidation. The proline content increased in drought-stressed plants and then decreased during the period of recovery. The high-resolution proteome map demonstrated significant variations in about 45 protein spots detected on Comassie briliant blue-stained 2-DE gels. Of these, 28 proteins were identified by mass spectrometry; the levels of 5 protein spots were increased, 21 were decreased and 2 spots were newly detected under drought condition. When the stress was terminated by watering the plants for 4 days, in most cases, the protein levels tended towards the control level. The proteins identified in this study are involved in a variety of cellular functions, including carbohydrate and nitrogen metabolism, cell wall modification, signal transduction, cell defense and programmed cell death, and they contribute to the molecular mechanism of drought tolerance in soybean plants. Analysis of protein expression patterns revealed that proteins associated with osmotic adjustment, defense signaling and programmed cell death play important roles for soybean plant drought adaptation. The identification of these proteins provides new insight that may lead to a better understanding of the molecular basis of the drought stress responses.     

Insight into the biochemical characterization of phytocystatin from Glycine max and its interaction with Cd+2 and Ni+2

Phytocystatins are cysteine proteinase inhibitors ubiquitously present in plants and animals. They are known to carry out various significant physiological functions and also maintain the balance of protease‐antiprotease activity. In the present disquisition, a phytocystatin after preliminary treatment has been isolated and purified to homogeneity from soybean (Glycine max) by a simple two‐step stratagem using ammonium sulfate fractionation and gel filtration chromatography performed on Sephacryl S‐100‐HR. Soybean phytocystatin (SBPC) was purified with a fold purification of 635 and percent yield of 77.6%. A single band was observed on native gel electrophoresis confirming the homogeneity of the purified SBPC. The molecular weight of SBPC was found to be 19.05 kDa as determined by SDS‐PAGE. The SBPC was found to be devoid of carbohydrate moieties and sulfhydryl group content. The binding stoichiometry of SBPC‐papain interaction was determined by isothermal calorimetry suggesting 1:1 complex, and the value of binding constant (K) was found to be 2.78 × 10⁵ M^?1 The affinity of binding (K_d) value obtained through ITC was 3.59 × 10^?6 M. The purified SBPC was found to be stable in the pH range of 3 to 7 and is thermostable up to 50°C. The UV‐visible and fluorescence studies showed significant changes in the conformation upon the formation of the SBPC‐papain complex. Furthermore, fluorescence spectroscopy, ANS binding, and caseinolytic activity assay were conducted out to explore the effect of metal ions on SBPC which showed that there was a loss in the inhibitory activity along with conformational changes of SBPC upon complex formation with Cd⁺² and Ni⁺².     

Virus elimination and pathogen-free plantlets regeneration in Cucurbita pepo L.

An efficient in vitro protocol was established for developing pathogen-free plantlets in Cucurbita pepo through meristem culture. Meristems of about 0.3–0.5 mm in size were isolated from shoot tips of 25–30 day old in vitro grown plants. For primary establishment of isolated apical meristem, MS liquid medium supplemented with 2.0 mgl KIN and 0.5 mg/l GA₃ was found to be most effective in both cultivars. MS semisolid medium containing 2.0 mg/l BAP were found to be most effective for shoot development from primarily established meristem in both cultivars. A good number of shoots were not concomitant with good rooting. The best root induction was found in media having 1.0 mg/l IBA in cv. Bulum. It was found that cv. Bulum was better than cv. Rumbo in all stages of meristem culture. The presence of virus in plantlets was achieved by DAS-ELISA test, where 68–81% plantlets have been proved to be virus free among the studied viruses. Healthy growth and vigour was observed in meristem derived plants over their source plants after cultivation under natural conditions.     

Characterization of a novel thiosulfate dehydrogenase from a marine acidophilic sulfur-oxidizing bacterium,Acidithiobacillus thiooxidans strain SH

A marine acidophilic sulfur-oxidizing bacterium, Acidithiobacillus thiooxidans strain SH, was isolated to develop a bioleaching process for NaCl-containing sulfide minerals. Because the sulfur moiety of sulfide minerals is metabolized to sulfate via thiosulfate as an intermediate, we purified and characterized the thiosulfate dehydrogenase (TSD) from strain SH. The enzyme had an apparent molecular mass of 44 kDa and was purified 71-fold from the solubilized membrane fraction. Tetrathionate was the product of the TSD-oxidized thiosulfate and ferricyanide or ubiquinone was the electron acceptor. Maximum enzyme activity was observed at pH 4.0, 40 °C, and 200 mM NaCl. To our knowledge, this is the first report of NaCl-stimulated TSD activity. TSD was structurally different from the previously reported thiosulfate-oxidizing enzymes. In addition, TSD activity was strongly inhibited by 2-heptyl-4-hydroxy-quinoline N-oxide, suggesting that the TSD is a novel thiosulfate:quinone reductase.     

Length–weight and length–length relationships of five Mystus species from the Ganges and Rupsha rivers,Bangladesh

This study focused on the length–weight and length–length relationships of five Mystus species from Bangladesh. A sum of 398 individuals (Mystus bleekeri = 47, Mystus cavasius = 171, Mystus gulio = 59, Mystus tengra = 65, and Mystus vittatus = 56) was collected from the Ganges and Rupsha rivers, Bangladesh. Fishes were caught by gill net (mesh sizes: 2.0–4.0 cm) and cast net (mesh sizes: 1.5–3.0 cm) from July 2014 to June 2015. Total length (TL), fork length (FL) and standard length (SL) were measured to 0.1 cm, while whole body weight (W) was taken to the nearest 0.1 g for each individual. The TL ranged from 6.0–13.5 cm for M. bleekeri, 5.0–15.0 cm for M. cavasius, 7.4–17.2 cm for M. gulio, 4.6–11.6 cm for M. tengra and 5.5–12.3 cm for M. vittatus. The W varied from 3.0–18.2 g for M. bleekeri, 1.3–30.4 g for M. cavasius, 6.1–62.2 g for M. gulio, 1.7–15.1 g for M. tengra and 2.7–19.2 g for M. vittatus. All LWRs were highly significant (p < .001), with all r² values ≥.950. The LLRs were also highly significant (p < .001), with all r² ≥.980. This study provides information on LWRs and LLRs for M. gulio and M. tengra for the first time. The results of this study can be very effective for stock assessment of Mystus species in the Ganges and Rupsha rivers as well as in the surrounding ecosystems.     

Synthesis, characterization, antibacterial and corrosion protective properties of epoxies, epoxy-polyols and epoxy-polyurethane coatings from linseed and Pongamia glabra seed oils

The aim of this paper is to investigate the structures and properties of epoxidized linseed and Pongamia glabra oils (LOE/POE), their derived products—epoxy-polyols (HLOE/HPOE), epoxy-polyurethanes (EU = LOPU/POPU) and EU coatings. Changes in epoxy equivalent, iodine value, hydroxyl value and percent saturation of oil backbone in due course of epoxidation and hydroxylation reactions, were plotted as a function of time. Spectral (IR, ¹H NMR and ¹³C NMR), physico-chemical and thermal (TGA and DSC) analyses of aforementioned resins were performed by standard methods. Physico-mechanical and chemical resistance tests reveal that coatings of LOPUs perform better than those of POPUs. It was found that properties of oil epoxy-polyurethane coatings are mainly governed by: (i) fatty acid composition and nature of starting oils, (ii) extent of epoxidation, (iii) number and location of hydroxyls and residual double bonds in the final product and (iv) the presence of long dangling chains. PO, HLOE and LOPUs exhibit good antibacterial activity against Escherichia coli at very small MIC. These EU systems can be safely employed unto 220 °C.     

RAGE in diabetic nephropathy

As is diabetes itself, diabetic angiopathy is a multi-factorial disease. Advanced glycation endproducts (AGE) cause vascular cell derangement characteristic of diabetes, and this is mainly mediated by their interaction with receptor for AGE (RAGE). When made diabetic, RAGE-overexpressing transgenic mice exhibited exacerbation of the indices of nephropathy, and this was prevented by the inhibition of AGE formation. On the other hand, RAGE-deficient animals showed amelioration of diabetic nephropathy. Accordingly, AGE and RAGE should be regarded as environmental and cellular accounts and as a potential therapeutic target for diabetic nephropathy. In effect, substances that inhibit the formation of AGE, break preformed AGE, change metabolic flows away from glycation, antagonize RAGE, and capture RAGE ligands have been proven as effective remedies against this life-threatening disease.