Oxidative stress parameters in blood, liver, and kidney of diabetic rats treated with curcumin and/or insulin

This study evaluated the effects of curcumin and/or insulin on antioxidant enzyme activity in blood, liver, and kidney, as well as on lipid peroxidation and delta aminolevulinic dehydratase (δ-ALA-D) activity, and a histopathological analysis of streptozotocin-induced diabetic rats. The animals were divided into six groups (n = 6): control/saline (C); control/curcumin (CCur); diabetic/saline (D); diabetic/insulin (DIns); diabetic/curcumin (DCur); and diabetic/insulin/curcumin (DInsCur). After 30 days of treatment with curcumin and/or insulin, the animals were sacrificed and the liver, kidney, and serum were used for experimental determinations. Results of histopathological analysis showed that the treatment with insulin ameliorate renal and hepatic lesions from both DIns and DInsCur groups. TBARS levels were significantly increased in serum, liver, and kidney in D group and the administration of curcumin and insulin prevented this increase in DIns and DCur groups. The activities of catalase (CAT), superoxide dismutase, and δ-ALA-D presented a significant decrease in the liver and kidney D group when compared to C group (P < 0.05). The animals treated with curcumin and insulin presented an increase of CAT activity, revealing a positive interaction between both substances. The treatments with curcumin or insulin prevented oxidative stress in blood, through modulation of enzymatic antioxidant defenses. These findings contributed to the comprehension that antioxidants from medicinal plants could be used as adjuvant in the treatment of this endocrinopathy and not as single therapy.     

Seasonal occurrences of <Emphasis Type="Italic">Manta birostris</Emphasis> (Chondrichthyes: Mobulidae) in southeastern Brazil

An analysis of 79 underwater photographs of Manta birostris gathered over a period of nine years in a marine protected area in southeastern Brazil suggests a high predictability of manta ray occurrences in the region during the austral winter (June–September). The reasons for this are probably related to the seasonal oceanographic conditions, as characterized by the presence of a coastal front at the study site in winter and consequent plankton enrichment, which provides a feeding opportunity for manta rays. In addition, a melanistic individual in the Atlantic Ocean that is similar in color to the Pacific Ocean’s “black manta” is reported for the first time.     

Cytosolic phospholipase A2-driven PGE2 synthesis within unsaturated fatty acids-induced lipid bodies of epithelial cells

Cytoplasmic lipid bodies (also known as lipid droplets) are intracellular deposits of arachidonic acid (AA), which can be metabolized for eicosanoid generation. PGE₂ is a major AA metabolite produced by epithelial cells and can modulate restoration of epithelium homeostasis after injury. We studied lipid body biogenesis and their role in AA metabolic pathway in an epithelial cell line derived from normal rat intestinal epithelium, IEC-6 cells. Lipid bodies were virtually absent in confluent IEC-6 cells. Stimulation of confluent IEC-6 cells with unsaturated fatty acids, including AA or oleic acid (OA), induced rapid lipid body assembly that was independent on its metabolism to PGE₂, but dependent on G-coupled receptor-driven signaling through p38, PKC, and PI3K. Newly formed lipid bodies compartmentalized cytosolic phospholipase (cPL)A₂-α, while facilitated AA mobilization and synthesis of PGE₂ within epithelial cells. Thus, both lipid body-related events, including highly regulated biogenesis and functional assembly of cPLA₂-α-driven enhanced AA mobilization and PGE₂ production, may have key roles in epithelial cell-driven inflammatory functions, and may represent relevant therapeutic targets of epithelial pathologies.     

Intraerythrocytic stages of Plasmodium falciparum biosynthesize menaquinone

Herein, we show that intraerythrocytic stages of Plasmodium falciparum have an active pathway for biosynthesis of menaquinone. Kinetic assays confirmed that plasmodial menaquinone acts at least in the electron transport. Similarly to Escherichia coli, we observed increased levels of menaquinone in parasites kept under anaerobic conditions. Additionally, the mycobacterial inhibitor of menaquinone synthesis Ro 48-8071 also suppressed menaquinone biosynthesis and growth of parasites, although off-targets may play a role in this growth-inhibitory effect. Due to its absence in humans, the menaquinone biosynthesis can be considered an important drug target for malaria.     

Evaluation of IDA-PEVA hollow fiber membrane metal ion affinity chromatography for purification of a histidine-tagged human proinsulin

Inabilities to process particulate material and to allow the use of high flow rates are limitations of conventional chromatography. Membranes have been suggested as matrix for affinity separation due to advantages such as allowing high flow rates and low-pressure drops. This work evaluated the feasibility of using an iminodiacetic acid linked poly(ethylenevinyl alcohol) membrane in the immobilized metal ion affinity chromatography (IMAC) purification of a human proinsulin(His)(6) of an industrial insulin production process. The screening of metal ions showed Ni(2+) as metal with higher selectivity and capacity among the Cu(2+), Ni(2+), Zn(2+) and Co(2+). The membrane showed to be equivalent to conventional chelating beads in terms of selectivity and had a lower capacity (3.68 mg/g versus 12.26 mg/g). The dynamic adsorption capacity for human proinsulin(His)(6) was unaffected by the mode of operation (dead-end and cross-flow filtration).     

Germination responses of native and invasive Cerrado grasses to simulated fire temperatures

Background: Fire is an important ecological factor in the Cerrado (Brazilian savanna). However, comparative studies on the effect of high temperatures experienced during fires on seed germination of native and invasive grass species are few.

Aims: To assess germination responses to simulated fire temperatures by seeds of invasive and native Cerrado grasses.

Methods: Heat-shock treatments (50 °C, 70 °C, 90 °C, 110 °C, 130 °C or 150 °C) were applied to seeds of 10 species of native and invasive grasses. For each temperature, the seeds were heated in a dry-air flow for 2 or 5 min. This combination of temperatures and exposure times simulated the soil conditions during typical Cerrado fires.

Results: Temperature treatment was significantly related to germination, and the effect varied according to species. Heat shock did not increase germination in either the native or the invasive species. Exposure time was important for only two species, and four species showed a significant increase in mean germination time.

Conclusions: Species showed different tolerances to high temperatures. It was not possible to differentiate the native and invasive grasses only by their tolerance to high temperatures, suggesting that fire alone may not be an efficient management tool to control the invasive species studied here.     

Overexpression, purification, and biochemical characterization of GumC, an enzyme involved in the biosynthesis of exopolysaccharide by Xylella fastidiosa

GumC is one of nine enzymes involved in the biosynthesis of fastidian gum, an exopolysaccharide produced by Xylella fastidiosa that may be linked directly to the pathogenicity of the microorganism. GumC may be responsible for gum polymerization or secretion through the membrane of X. fastidiosa. To perform structure and functions studies, we developed an expression system for the production of GumC as a fusion protein with maltose binding protein (MBP) using pMAL-c2x vector. The GumC-MBP fusion protein was expressed as a 94 kDa protein, which strongly reacts with anti-MBP antibodies. GumC-MBP was isolated by affinity chromatography through an amylose column and used to produce antibodies against the fusion protein. After the enzymatic cleavage of MBP, GumC was purified on a Q Sepharose Fast Flow column. GumC showed a molecular weight corresponding to the expected one (52 kDa) and its N-terminal sequence was identical to that deduced from the DNA. The shape of the circular dichroism spectrum was compatible with a folded protein that contains alpha-helical regions in its structure. Therefore, in this study we describe, for the first time, the production of GumC recombinant protein.     

Maytenus obtusifolia Mart. (Celastraceae): a tropical woody species in a transitional evolutionary stage of the gynodioecy–dioecy pathway

‘Gynodioecy–dioecy’ is one of the pathways by which dioecy can arise from hermaphroditism. Studies on sex determination and development of gynodioecious systems have focused on temperate and/or annual species. Little is known about the evolutionary dynamics of gynodioecy and dioecy in perennial tropical species, where these systems have more frequently evolved. Maytenus obtusifolia is an abundant species in restingas in southeastern Brazil. The sexual system of M. obtusifolia was investigated by studying the floral structure and reproductive biology. We considered the sexual system as an intermediate step in the pathway gynodioecy-dioecy. The characterization of the hermaphrodite morph was complex, because of a gradient of variation in floral morphology and reproductive characteristics (sizes of the style and stigmatic surface, pollen viability, embryo sacs containing hypertrophied synergids, and fruit set). This variation leads to different proportions of functional male and female flowers among hermaphrodite plants and is responsible for the different levels of reproductive success. Female reproductive success and pollen viability were negatively correlated with the hermaphrodite morph (r = ?0.67). The higher fruiting intensity and fruit/flower ratio of females (41 %) compared to hermaphrodites (2 %) and the fact that female plants produce more and better-quality seeds support the female compensation. We suggest that female sterility may be linked to the set of changes in the carpels. The differences in the quality and quantity of pollen grains of hermaphrodite plants, and the similar individual rates of pollen viability observed for three consecutive flowering events, may indicate a relationship with nuclear cytoplasmic sex determination.     

What happens when fire is too early? Observations of fire-stimulated fruit opening releasing underdeveloped seeds for an endemic Cerrado shrub

The relation of fire with the reproductive process of species from tropical grasslands and savannas has long been investigated. Post-fire flowering is well documented in the Cerrado, but fire-mediated fruit opening and seed dispersal has rarely been described, with very few historical records being known. Even less is known about the effects of different fire seasons on species reproduction. Here, we describe the fire-stimulated fruit opening of Jacaranda ulei, an endemic Cerrado shrub with medical importance to traditional communities. We show that fruits opened within 2 weeks after an early dry season fire, but there were almost no viable seeds as fruits were still immature when burned. When put together with the known records for other species, dry dehiscent fruits and anemochory arise as common traits that favour fire-mediated fruit opening. As these are common attributes in the Cerrado, it is possible that several other species also have fire-stimulated seed dispersal but remain vastly unnoticed and underreported in the literature. Additionally, the peak reproductive effort of these species coincides with the period of prescribed burns of the Integrated Fire Management Program and, consequently, several species could also have their reproductive cycle interrupted to disperse immature seeds. We hope our note encourages further studies on the fire-mediated fruit opening and seed dispersal of Cerrado species, particularly in relation to fire season and seed quality.     

Expression,refolding, and in vitro activation of a recombinant snake venom pro-metalloprotease

Metalloproteases comprise a family of Zn(2+)-endopeptidases that degrade most components of the extracellular matrix. Snake venoms are rich sources of metalloproteases, which also digest fibrinogen as well as fibrin, and in some cases, induce hemorrhage. A few low-molecular weight snake venom metalloproteases (svMPs) have been described as being devoid of hemorrhagic activity, but they have strong direct-acting fibrinolytic activity. This property could be very helpful in thrombosis therapy. ACLF is a fibrinolytic, non-hemorrhagic metalloprotease from the venom of the North American snake Agkistrodon contortrix laticinctus. We have developed an expression system for production of a recombinant pro-ACLF from a clone (ACLPREF) isolated from a venom gland cDNA library. The coding region including both the pro-enzyme domain and the mature protein domain was amplified by PCR and subcloned into the pET28a vector and the new plasmid was used to transform BL21(DE3) Escherichia coli cells. Culture of the transformants at 37 degrees C led to the overexpression of an insoluble 48kDa protein after induction with 1.0mM IPTG. The expressed protein was recovered from inclusion bodies with 6M buffered urea and purified by affinity chromatography under denaturing conditions. After dithiothreitol treatment, protein refolding was performed by gradual removal of the denaturing agent by dialysis. The pro-enzyme underwent auto-activation during refolding and it was active on fibrinogen and on a synthetic substrate. To control the activation step, the denaturing agent was rapidly removed to keep the protein in an unprocessed form, followed by later addition of Ca(2+) and Zn(2+) ions. This allowed controlling the enzyme activation, when it is needed.