Disturbance‐modulated symbioses in termitophily

Symbiosis, the living‐together of unlike organisms, underlies every major transition in evolution and pervades most ecological dynamics. Among examples of symbioses, the simultaneous occupation of a termite nest by its builder termites and intruding invertebrate species (so‐called termitophily) provides suitable macroscopic scenarios for the study of species coexistence in confined environments. Current evidence on termitophily abounds for dynamics occurring at the interindividual level within the termitarium, but is insufficient for broader scales such as the community and the landscape. Here, we inspect the effects of abiotic disturbance on termitophile presence and function in termitaria at these broader scales. To do so, we censused the termitophile communities inhabiting 30 termitaria of distinct volumes which had been exposed to increasing degrees of fire‐induced disturbance in a savanna‐like ecosystem in southeastern Brazil. We provide evidence that such an abiotic disturbance can ease the living‐together of termitophiles and termites. Putative processes facilitating these symbioses, however, varied according to the invader. For nonsocial invaders, disturbance seemed to boost coexistence with termites via the habitat amelioration that termitaria provided under wildfire, as suggested by the positive correlation between disturbance degree and termitophile abundance and richness. As for social invaders (ants), disturbance seemed to enhance associational defenses with termites, as suggested by the negative correlation between the presence of ant colonies and the richness and abundance of other termitarium‐cohabiting termitophiles. It is then apparent that disturbance‐modulated distinct symbioses in these termite nests.     

Trap-nests used by Centris (Heterocentris) terminata Smith (Hymenoptera: Apidae, Centridini) at secondary Atlantic Forest fragments, in Salvador, Bahia State

Ninety-five nests of Centris (Heterocentris) terminata Smith were collected in trap-nests, during November/2001 and January/2003, at two fragments (PZGV e CFO-UFBA) of secondary Atlantic Forest, in Salvador, Bahia State (13 masculine01 W e 38 masculine30 S). The highest nest frequencies occurred from December to February (summer), with no nests foundations from August to October (winter - early spring). Two-hundred eight adults emerged from 347 brood cells, being 164 males and 116 females (1: 0.42). During the study period sex ratio was male biased (c2 = 9.342; gl = 10; P < 0.05). C. terminata nested in holes with diameters 6, 8, 10 mm, but 84,2% were constructed in 8 and 10 mm. nests had one to seven cells arranged in a linear series with the cells partitions built with a mixture of sand and resin or oil. Male is significantly smaller than female, which emerges from the first cells constructed. Immature mortality occurred in 14.1% of brood cells (n = 49), of which 13.0% were due fail in development and 1.2% due to parasitism of Coelioxys sp. (Hymenoptera: Megachilidae) e Tetraonyx sp. (Coleoptera: Meloidae). In the study site, weather, mainly pluviosity, rather than natural enemies influenced seasonal population abundance. The long period of nesting activity, local abundance and usage of trap nests, suggest the potential of C. terminata for management aiming at pollination of native and cultivated plants.     

Preservation of bovine preantral follicle viability and ultra-structure after cooling and freezing of ovarian tissue

Bovine preantral follicles within ovarian fragments were exposed and cryopreserved in absence or presence of 1.5 M glycerol (GLY), ethylene glycol (EG), propanediol (PROH) or dimethyl sulfoxide (DMSO), undergoing a previous cooling at 20 °C for 1 h (protocol 1) or at 4 °C for 24 h (protocol 2) in 0.9% saline solution. At the end of each treatment, preantral follicles were classified as non-viable/viable when they were stained/not stained with trypan blue, respectively. To confirm viability staining, ultra-structure of the follicles was evaluated by transmission electronic microscopy (TEM). Data were compared by Chi-square test (P < 0.05). The storage of the ovaries at 20 °C for 1 h (78%) and 4 °C for 24 h (80%) did not reduce significantly the percentage of viable preantral follicles when compared to the control (75%). Similar results were obtained when ovarian fragments, respectively, for protocols 1 and 2, were exposed to MEM (78 and 77%), 1.5 M EG (78 and 71%), as well as frozen in 1.5 M EG (74 and 77%). Percentages of viable follicles in control were similar to those observed after exposure (75%) and freezing (76%) in presence of 1.5 M DMSO only when protocol 1 was used. The increase of the concentration from 1.5 to 3.0 M, for all cryoprotectants, reduced significantly the percentage of viable preantral follicles after freezing. Ultra-structural analysis has confirmed trypan blue results, showing that not only basement membrane, but also organelles, were intact in viable preantral follicles. In conclusion, ovarian tissue cooling at 4 °C for 24 h before cryopreservation (protocol 2) does not affect the viability of bovine preantral follicles when 1.5 M EG is present in the cryopreservation medium.     

Guarana (Paullinia cupana var. sorbilis), an anciently consumed stimulant from the Amazon rain forest: the seeded-fruit transcriptome

Guarana (Paullinia cupana var. sorbilis) is a plant native to the central Amazon basin. Roasted seed extracts have been used as medicinal beverages since pre-Colombian times, due to their reputation as stimulants, aphrodisiacs, tonics, as well as protectors of the gastrointestinal tract. Guarana plants are commercially cultivated exclusively in Brazil to supply the national carbonated soft-drink industry and natural product stores around the world. In this report, we describe and discuss the annotation of 15,387 ESTs from guarana seeded-fruits, highlighting sequences from the flavonoid and purine alkaloid pathways, and those related to biotic stress avoidance. This is the largest set of sequences registered for the Sapindaceae family.     

Diurnal Rhythms of Plasma Ions and Metabolites Levels in Thoroughbred Racehorses

The purposes of this study were to observe the presence of diurnal rhythms in plasma ions and metabolites levels in Thoroughbred racehorses under physical training, and to determine the time of blood sampling in clinical investigations. Plasma calcium, phosphorus, potassium, sodium, chloride, magnesium, iron, glucose, cholesterol, triglycerides, and total proteins levels were studied over a 72-h period. Blood samples were taken every 4 hours from five male and five female Thoroughbred racehorses under physical training. COSINOR analyses (P = 0.05) were done. Plasma potassium and triglycerides showed significant diurnal rhythms, with its acrophases occurring at dark period. No significant diurnal rhythms of other variables were found. It was concluded that, in Thoroughbred racehorses, the optimum time for potassium, and triglycerides sampling seems to be light period. And for other variables, time of diagnosis is not important.     

Naphtho[2,3-d]isoxazole-4,9-dione-3-carboxylates: Potent, non-cytotoxic, antiapoptotic agents

Compounds containing a quinone moiety represent an important class of biologically active molecules that are widespread in nature, displaying anticancer, antibacterial, antimalarial, and fungicidal activities. In the course of designing 2,3-disubstituted-1,4-naphthoquinones derivatives as potential cysteine protease inhibitors, two naphtho[2,3-d]isoxazole-4,9-dione-3-carboxylates, 1a and 1b, were obtained. The antiapoptotic potential of 1a and 1b was then evaluated and compared to that of naphthoquinone 4. Primary rat hepatocytes were incubated with synthesized naphthoquinone derivatives and then exposed to the apoptotic stimulus camptothecin. Our results indicate that naphtho[2,3-d]isoxazole-4,9-dione-3-carboxylates 1a and 1b exerted a potent protective role in camptothecin-induced apoptosis in primary rat hepatocytes. Both 1a and 1b significantly increased cell viability, while reducing nuclear fragmentation, caspase-3, -8 and -9 activation, and cytochrome c release induced by camptothecin. In addition, 1a and 1b were shown to up-regulate Bcl-X_L, a pro-survival member of the Bcl-2 family of proteins, which modulates the mitochondrial pathway of apoptosis. Similar protective effects of quinone derivatives were seen in HuH-7 and PC12 cells incubated with distinct apoptotic stimuli, such as camptothecin, TGF-β1, or rotenone. Our results suggest that naphtho[2,3-d]isoxazole-4,9-dione-3-carboxylates 1a and 1b may act as potent, cytoprotective agents, through modulation of apoptotic pathways.     

Neuroprotective Effects of Chalcones from <Emphasis Type="Italic">Myracrodruon urundeuva</Emphasis> on 6-Hydroxydopamine-Induced Cytotoxicity in Rat Mesencephalic Cells

In the present work, we showed that a chalcone-enriched fraction (CEF) isolated from the stem bark of a Brazilian medicinal plant, Myracrodruon urundeuva, presents neuroprotective actions on 6-hydroxydopamine (6-OHDA)-induced neuronal cell death, in rat mesencephalic cells. In the MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium] assay, which is an index of cell viability, CEF (1–100 μg/ml) reversed in a concentration-dependent manner the 6-OHDA-induced cell death. While cells exposed to 6-OHDA (40 μM) showed an increased concentration of thiobarbituric acid reactive substances (TBARS), the pretreatment with CEF (10–100 μg/ml) significantly decreased the 6-OHDA-induced TBARS formation, indicative of a neuroprotection against lipoperoxidation. Furthermore, the drastic increase of nitrite levels induced by 6-OHDA, indicative of nitric oxide formation and free radicals production, was prevented by CEF. Double staining with acridine orange/ethidium bromide showed that cultures exposed to 6-OHDA (40 and 200 μM) presented an increase of apoptotic and necrotic cell numbers in a concentration-dependent manner. CEF (100 μg/ml) protected cells from apoptosis and necrosis and increased number of cells presenting a normal morphology. The immunohistochemical analysis for tyrosine hydroxylase (TH) positive neurons indicated that 6-OHDA (40 and 200 μM) caused a concentration-dependent loss of TH+ and TH− neurons. CEF protected both cells types from 6-OHDA-induced cell death. All together, our results demonstrated neuroprotective effects of chalcones, which are able to reduce oxidative stress and apoptotic injury caused by 6-OHDA. Our findings suggest that chalcones could provide benefits, along with other therapies, in neurodegenerative injuries, such as Parkinson’s disease.     

Nitric oxide regulates steroid synthesis by bovine antral granulosa cells in a chemically defined medium

Nitric oxide (NO) in bovine ovary has been characterized as one of the controllers of granulosa cells’ (GC) steroidogenesis and apoptosis. One of the pathways used by NO to have these effects is cGMP. The objectives of the present study were to verify the effect of sodium nitroprusside (SNP), a NO donor, on steroidogenesis, cell viability (mitochondrial activity) and GC cell cycle distribution and if this effect occurs by the NO-cGMP signaling pathway with the addition of SNP with or without 1H-[1,2,3] oxadiaziolo[4,3a]quinoxaline-1-one (ODQ), a selective soluble guanylate cyclase inhibitor. The antral GC from 3 to 5 mm diameter cattle follicles was cultured without treatment (control), with ODQ (10⁻⁴ M) and 10⁻⁵, 10⁻³ and 10⁻¹ M SNP with or without ODQ for 24 h. Nitrate/nitrite (NO₃⁻/N0₂⁻) concentrations were evaluated by Griess method, progesterone (P₄) and 17β-estradiol (E₂) concentrations by chemiluminescence, viability and cell cycle stage by MTT method (3-[4,5-dimethylthiazol-2yl]-2,3 dipheniltetrazolium bromide) and flow cytometry, respectively. Nitrate/nitrite concentration in culture medium increased (P < 0.05) in a dose-dependent manner according to SNP concentration added to the culture medium. The GC cultured without treatment, with ODQ and with 10⁻⁵ M SNP in the presence or absence of ODQ developed into cell aggregates and did not vary in cell viability (P > 0.05), while GC cultured with 10⁻³ and 10⁻¹ M SNP with or without ODQ presented disorganized GC aggregates or did not develop into cell aggregates and also had substantially decreased cell viability (mitochondrial activity inhibition) and steroids synthesis (P < 0.05), and effects were not reversed with us of ODQ. Most GC cultured without treatment (control) or with ODQ, 10⁻⁵ and 10⁻³ M SNP with or without ODQ were in the G0/G1 (80–75%) stage and in a lesser proportion (20–25%) in the S + G2/M stage of the cell cycle, while the 10⁻¹ M SNP treatment resulted in GC in G1 phase arrest. The treatment with 10⁻⁵ M SNP increased (P < 0.05) E₂ synthesis and inhibited (P < 0.05) progesterone synthesis. The addition of ODQ reversed (P < 0.05) the stimulatory effect of 10⁻⁵ M SNP treatment on E₂, but not on P₄ synthesis (P > 0.05). These results demonstrated that E₂ synthesis by antral GC from small follicles is modulated by lesser NO concentrations via the cGMP pathway, but not P₄ while steroids inhibition cGMP pathway independent, mitochondrial damage and the interference on cell cycle progression caused by greater NO concentration can lead to cell death.     

Effect of inhibition of synthesis of inducible nitric oxide synthase-derived nitric oxide by aminoguanidine on the in vitro maturation of oocyte-cumulus complexes of cattle

The aim of the present study was to investigate the effects of inhibition of the enzyme inducible nitric oxide synthase (iNOS) by aminoguanidine (AG) on the in vitro maturation of oocyte-cumulus cell complex(es) (COC) of cattle. COC were cultured with different concentrations of AG (0, 1, 10, and 100mM) for 24h. In Experiment 1, the extent of cumulus complex expansion, nuclear maturation status and plasma membrane integrity of oocytes and cumulus cells from each treatment were assessed. Nitrate/nitrite (NO(3)(-)/NO(2)(-)) concentrations were determined in culture medium by the Griess method. Addition of different concentrations of AG to maturation medium promoted a dose-response inhibitory effect on cumulus expansion (P<0.05). Addition of 1 and 10mM AG to IVM medium did not affect plasma membrane integrity of oocytes or nuclear maturation rates (P>0.05), but it did reduce plasma membrane integrity in cumulus cells. One hundred millimolar inhibited pre-metaphase I (pre-MI) to metaphase II (MII) transition, promoted plasma membrane damage in oocytes (P<0.05), and increased NO(3)(-)/NO(2)(-) concentration when compared to controls (P<0.05). To evaluate if this effect was reversible, 10(-5)M sodium nitroprusside (SNP, NO donor) was added, only in the treatment with 100mM AG that inhibited the nuclear maturation. However, association of 10(-5)M SNP to 100mM AG did not reverse the effects of AG, but increased NO(3)(-)/NO(2)(-)concentration (P<0.05). In Experiment 2, the effect of different AG concentrations on cytoplasmic maturation in vitro was assessed based on cortical granule migration, and embryonic development. There was a dose effect on cortical granule migration rate, in which 1mM AG (83.9+/-6.2%) did not differ from control oocytes (83.6+/-8.2%; P>0.05), but 10mM partially inhibited migration (3.8+/-6.4%) and 100mM totally inhibited migration (P<0.05). SNP (10(-5)M) did not revert this inhibitory effect on cortical granules migration in oocytes treated with 100mM AG. Only those concentrations that did not inhibit IVM were used to assess cleavage and blastocyst development. Addition of 10mM AG to IVM medium reduced (73.0+/-8.1%, 15.0+/-8.9%; P<0.05) cleavage and blastocyst development, respectively when compared with controls (89.1+/-3.4%, 37.6+/-7.3%, respectively), but did not differ, (P>0.05), from the group treated with 1mM AG (80.9+/-8.4%, 41.5+/-10.5%, respectively). The results from the present study demonstrate that NO derived from iNOS affects the in vitro maturation of bovine COC, modulating the viability of cumulus cells and of oocyte, the progression of meiosis after GVBD, the migration of cortical granules, and cleavage and blastocyst development.     

A VANADIUM BROMOPEROXIDASE CATALYZES THE FORMATION OF HIGH‐MOLECULAR‐WEIGHT COMPLEXES BETWEEN BROWN ALGAL PHENOLIC SUBSTANCES AND ALGINATES1

The interaction between phenolic substances (PS) and alginates (ALG) has been suggested to play a role in the structure of the cell walls of brown seaweeds. However, no clear evidence for this interaction was reported. Vanadium bromoperoxidase (VBPO) has been proposed as a possible catalyst for the binding of PS to ALG. In this work, we studied the interaction between PS and ALG from brown algae using size exclusion chromatography (SEC) and optical tweezers microscopy. The analysis by SEC revealed that ALG forms a high‐molecular‐weight complex with PS. To study the formation of this molecular complex, we investigated the in vitro interaction of purified ALG from Fucus vesiculosus L. with purified PS from Padina gymnospora (Kütz.) Sond., in the presence or absence of VBPO. The interaction between PS and ALG only occurred when VBPO was added, indicating that the enzyme is essential for the binding process. The interaction of these molecules led to a reduction in ALG viscosity. We propose that VBPO promotes the binding of PS molecules to the ALG uronic acids residues, and we also suggest that PS are components of the brown algal cell walls.