Size fractionated phytoplankton production in two humic shallow lakes with contrasting coverage of free floating plants

We conducted a 1-year survey in two humic shallow lakes from the floodplain of the Lower Paraná River, Laguna Grande Lake (LGL) and a relictual oxbow lake (ROL). We aimed to test two hypotheses: (1) the efficiency in light use of picoplankton (0.2–3 μm) is greater as light restriction increases and (2) the contribution of picoplankton to the total productivity is higher when the total photosynthetic biomass is lower. We performed P–E curves for picoplankton and nano- and microplankton (>3 μm) using the ¹⁴C assimilation technique. The light environments of the water bodies differed mainly owing to the development of free floating plants on the surface of the ROL and the dominance of phytoplankton in LGL. Primary productivity patterns in LGL were seasonality driven whilst in the ROL they were related to the coverage of floating macrophytes, which promoted light limitation and a lower productivity. In LGL, nano- and microplankton were in general more productive and the relative contribution of picoplankton to the total phytoplankton production decreased with the increase in total photosynthetic biomass. Hence, our study extends previously observed patterns to subtropical shallow lakes, where seasonality and free floating plants may influence the dynamics of phytoplankton production.     

Interference of some aqueous two-phase system phase-forming components in protein determination by the Bradford method

The interference of some specific aqueous two-phase system (ATPS) phase-forming components in bovine serum albumin (BSA) determination by the Bradford method was investigated. For this purpose, calibration curves were obtained for BSA in the presence of different concentrations of salts and polymers. A total of 19 salts [Na₂SO₄, (NH₄)₂SO₄, MgSO₄, LiSO₄, Na₂HPO₄, sodium phosphate buffer (pH 7.0), NaH₂PO₄, K₂HPO₄, potassium phosphate buffer (pH 7.0), KH₂PO₄, C₆H₈O₇, Na₃C₆H₅O₇, KCHO₂, NaCHO₂, NaCO₃, NaHCO₃, C₂H₄O₂, sodium acetate buffer (pH 4.5), and NaC₂H₃O₂] and 7 polymers [PEG 4000, PEG 8000, PEG 20000, UCON 3900, Ficoll 70000, PES 100000, and PVP 40000] were tested, and each calibration curve was compared with the one obtained for BSA in water. Some concentrations of salts and polymers had considerable effect in the BSA calibration curve. Carbonate salts were responsible for the highest salt interference, whereas citric and acetic acids did not produce interference even in the maximum concentration level tested (5 wt%). Among the polymers, UCON gave the highest interference, whereas Ficoll did not produce interference when used in concentrations up to 10 wt%. It was concluded that a convenient dilution of the samples prior to the protein quantification is needed to ensure no significant interference from ATPS phase-forming constituents.     

Hemorrhagic activity of HF3, a snake venom metalloproteinase: insights from the proteomic analysis of mouse skin and blood plasma

Hemorrhage induced by snake venom metalloproteinases (SVMPs) is a complex phenomenon resulting in capillary disruption and blood extravasation. The mechanism of action of SVMPs has been investigated using various methodologies however the precise molecular events associated with microvessel disruption remains not fully understood. To gain insight into the hemorrhagic process, we analyzed the global effects of HF3, an extremely hemorrhagic SVMP from Bothrops jararaca, in the mouse skin and plasma. We report that in the HF3-treated skin there was evidence of degradation of extracellular matrix (collagens and proteoglycans), cytosolic, cytoskeleton, and plasma proteins. Furthermore, the data suggest that direct and indirect effects promoted by HF3 contributed to tissue injury as the activation of collagenases was detected in the HF3-treated skin. In the plasma analysis after depletion of the 20 most abundant proteins, fibronectin appeared as degraded by HF3. In contrast, some plasma proteinase inhibitors showed higher abundance compared to control skin and plasma. This is the first study to assess the complex in vivo effects of HF3 using high-throughput proteomic approaches, and the results underscore a scenario characterized by the interplay between the hydrolysis of intracellular, extracellular, and plasma proteins and the increase of plasma inhibitors in the hemorrhagic process.     

BJ-PI2, A non-hemorrhagic metalloproteinase from Bothrops jararaca snake venom

Background

Envenoming by Bothrops jararaca can result in local pain, edema, hemorrhage and necrosis, partially mediated by snake venom metalloproteinases (SVMPs). Here, we describe the characterization of BJ-PI2, a P-I class SVMP from B. jararaca venom, and its local tissue actions.

Methods

BJ-PI2 was purified by a combination of gel filtration, anion-exchange chromatography and reverse phase HPLC, and identified by mass spectrometry. Clotting and fibrin(ogen)olytic activities were assayed using conventional methods. Hemorrhagic activity and changes in vascular permeability were examined in rat dorsal skin. Myonecrosis and inflammatory activity were examined in mouse gastrocnemius muscle.

Results

BJ-PI2 was a 23.08 kDa single-chain polypeptide. Tryptic fragments showed highest homology with SVMP insularinase A from Bothrops insularis, but also with B. jararaca SVMP bothrojaractivase; less similarity was observed with B. jararaca SVMPs BJ-PI and jararafibrases II and IV. BJ-PI2 did not clot fibrinogen or rat citrated plasma but had α- and β-fibrinogenolytic activity (inhibited by EDTA and 1,10-phenanthroline but not by PMSF) and attenuated coagulation after plasma recalcification. BJ-PI2 had fibrinolytic activity. BJ-PI2 increased the vascular permeability of rat dorsal skin (inhibited by 1,10-phenanthroline). BJ-PI2 was not hemorrhagic or myonecrotic but caused migration of inflammatory cells. In contrast, venom was strongly hemorrhagic and myonecrotic but caused less infiltration of inflammatory cells.

Conclusions

BJ-PI2 is a non-hemorrhagic, non-myonecrotic, non-coagulant P-I class SVMP that may enhance vascular permeability and inflammatory cell migration in vivo.

General significance

BJ-PI2 contributes to enhanced vascular permeability and inflammatory cell migration after envenoming, but not to venom-induced hemorrhage and necrosis.     

Iron,Copper, and Zinc Transport: Inhibition of Divalent Metal Transporter 1 (DMT1) and Human Copper Transporter 1 (hCTR1) by shRNA

Iron (Fe), copper (Cu), and zinc (Zn) fulfill various essential biological functions and are vital for all living organisms. They play important roles in oxygen transport, cell growth and differentiation, neurotransmitter synthesis, myelination, and synaptic transmission. Because of their role in many critical functions, they are commonly used in food fortification and supplementation strategies globally. To determine the involvement of divalent metal transporter 1 (DMT1) and human copper transporter 1 (hCTR1) on Fe, Cu, and Zn uptake, Caco-2 cells were transfected with four different shRNA plasmids to selectively inhibit DMT1 or hCTR1 transporter expression. Fe and Cu uptake and total Zn content measurements were performed in shRNA-DMT1 and shRNA-hCTR1 cells. Both shRNA-DMT1 and shRNA-hCTR1 cells had lower apical Fe uptake (a decrease of 51% and 41%, respectively), Cu uptake (a decrease of 25.8% and 38.5%, respectively), and Zn content (a decrease of 23.1% and 22.7%, respectively) compared to control cells. These results confirm that DMT1 is involved in active transport of Fe, Cu, and Zn although Zn showed a different relative capacity. These results also show that hCTR1 is able to transport Fe and Zn.     

Type 2 diabetic patients and their offspring show altered parameters of iron status, oxidative stress and genes related to mitochondrial activity

Type 2 diabetes (T2D) is directly related to alterations in iron status, oxidative stress and decreased mitochondrial activity, but the possible interaction of these parameters among T2D patients and their offspring is unclear. The whole study included 301 subjects: 77 T2D patients and one of their offspring and 51 control subjects with one of their offspring. The offspring were older than 20?years old. We measured parameters of iron status (serum iron, ferritin and transferrin receptor), diabetes (pre and post-prandial glucose, insulin, lipids), oxidative stress (Heme oxygenase activity, TBARS, SOD, GSH, Vitamin E), as well as the expression of genes in blood leukocytes related to mitochondrial apopotosis (mitofusin and Bcl/Bax ratios). The offspring of T2D patients had increased levels of serum ferritin (P?相似文献   

Mefloquine-oxazolidine derivatives, derived from mefloquine and arenecarbaldehydes: In vitro activity including against the multidrug-resistant tuberculosis strain T113

Ten new mefloquine-oxazolidine derivatives, 4-[(1S,8aR)-3-(aryl)hexahydro[1,3]oxazolo[3,4-a]pyridin-1-yl]-2,8-bis(trifluoromethyl)quinoline (1: aryl=substituted phenyl) and 4-[(1S,8aR)-3-(heteroaryl)hexahydro[1,3]oxazolo[3,4-a]pyridin-1-yl]-2,8-bis(trifluoromethyl)quinoline [2: heteroaryl=5-nitrothien-2-yl (2a); 5-nitrofuran-2-yl (2b) and 4H-imidazol-2-yl) (2c)], have been synthesized and evaluated against Mycobacterium tuberculosis. Compounds 1f (aryl=3-ethoxyphenyl), 1g (Ar=3,4,5-(MeO)(3)-C(6)H(2)) and 2c were slightly more active than mefloquine (MIC=33μM) with MICs=24.5, 22.5 and 27.4, respectively, whereas compounds 1e (aryl=3,4-(MeO)(2)-C(6)H(3)) and 2a (MICs=11.9 and 12.1μM, respectively) were ca. 2.7 times more active than mefloquine, with a better tuberculostatic activity than the first line tuberculostatic agent ethambutol (MIC=15.9). The compounds were also assayed against the MDR strain T113 and the same MICs were observed. Thus the new derivatives have advantages over such anti-TB drugs as isoniazid, rifampicin, ethambutol and ofloxacin, for which this strain is resistant. The most active compounds were not cytotoxic to Murine Macrophages Cells in a concentration near their MIC values.     

Histoplasmosis as cause of penile ulcer in acquired immune deficiency syndrome (AIDS): three case reports

Background Histoplasma capsulatum is the causative agent of American histoplasmosis. The relationship between disseminated histoplasmosis and AIDS has been well established. Widespread hematogenous dissemination of Histoplasma capsulatum in HIV positive patients can cause a plethora of clinical manifestations; virtually any organic system can be affected. However, genital ulceration by H. capsulatum in patients with AIDS is a real challenge during investigation of the infection due to the great variety of differential diagnoses that are involved. Method The diagnosis was performed by histopathologic study; H. capsulatum was detected by silver staining (Grocott staining) and confirmed by immunocytochemistry. Results We report three cases of histoplasmosis in patients with AIDS, in which we observed genital ulcers, an unusual form of presentation of this disease. In one of these cases, the treatment resulted in total cure. Conclusion The cases reported herein are to illustrate the plurality of pathologies and clinical manifestations, which may affect immunocompromised patients. The correct diagnosis of fungal diseases in these patients following well established treatment will improve the prognosis.