Peripheral neuronal nitric oxide synthase activity mediates the antinociceptive effect of Crotalus durissus terrificus snake venom, a delta- and kappa-opioid receptor agonist

Previous work has shown that nitric oxide (NO) mediates the antinociceptive effect of Crotalus durissus terrificus venom on carrageenin-induced hyperalgesia. In the present study the role of constitutive neuronal or of inducible form of nitric oxide synthase on venom effect was determined. The rat paw prostaglandin E(2) (PGE(2))-induced mechanical hyperalgesia model was used for nociceptive evaluation. The venom (200 microg/kg) administered per oz immediately before prostaglandin induced antinociception that persisted for 120 h. The characterisation of the antinociceptive effect of the venom in this model of hyperalgesia showed that kappa and delta-opioid receptors are involved in this effect. 7-nitroindazole (7-NI), a neuronal nitric oxide synthase (NOS) inhibitor, but not L-N(6)-(1-iminoethyl)lysine (L-NIL), an inhibitor of the inducible form of NOS, injected by intraplantar (i.pl.) route, antagonized the antinociceptive effect of the venom. The i.pl. administration of 1H-(1,2,4)oxadiazolo[4,3-a]quinoxaline-1-one (ODQ), a selective guanylate cyclase inhibitor, blocked antinociception, whereas Rp-cGMP triethylamine, a cGMP-dependent protein kinase inhibitor, partially reversed this effect. These data indicate that peripheral kappa- and delta-opioid receptors are involved in the antinociceptive effect of Crotalus durissus terrificus on prostaglandin E(2)-induced hyperalgesia. Peripheral nitric oxide, generated by neuronal NO synthase, and cGMP/PKc are responsible, at least partially, for the molecular mechanisms of venom effect.     

Prevalence of trypanosomes,salivary gland hypertrophy virus and Wolbachia in wild populations of tsetse flies from West Africa

Background

Tsetse flies are vectors of African trypanosomes, protozoan parasites that cause sleeping sickness (or human African trypanosomosis) in humans and nagana (or animal African trypanosomosis) in livestock. In addition to trypanosomes, four symbiotic bacteria Wigglesworthia glossinidia, Sodalis glossinidius, Wolbachia, Spiroplasma and one pathogen, the salivary gland hypertrophy virus (SGHV), have been reported in different tsetse species. We evaluated the prevalence and coinfection dynamics between Wolbachia, trypanosomes, and SGHV in four tsetse species (Glossina palpalis gambiensis, G. tachinoides, G. morsitans submorsitans, and G. medicorum) that were collected between 2008 and 2015 from 46 geographical locations in West Africa, i.e. Burkina Faso, Mali, Ghana, Guinea, and Senegal.

Results

The results indicated an overall low prevalence of SGHV and Wolbachia and a high prevalence of trypanosomes in the sampled wild tsetse populations. The prevalence of all three infections varied among tsetse species and sample origin. The highest trypanosome prevalence was found in Glossina tachinoides (61.1%) from Ghana and in Glossina palpalis gambiensis (43.7%) from Senegal. The trypanosome prevalence in the four species from Burkina Faso was lower, i.e. 39.6% in Glossina medicorum, 18.08%; in Glossina morsitans submorsitans, 16.8%; in Glossina tachinoides and 10.5% in Glossina palpalis gambiensis. The trypanosome prevalence in Glossina palpalis gambiensis was lowest in Mali (6.9%) and Guinea (2.2%). The prevalence of SGHV and Wolbachia was very low irrespective of location or tsetse species with an average of 1.7% for SGHV and 1.0% for Wolbachia. In some cases, mixed infections with different trypanosome species were detected. The highest prevalence of coinfection was Trypanosoma vivax and other Trypanosoma species (9.5%) followed by coinfection of T. congolense with other trypanosomes (7.5%). The prevalence of coinfection of T. vivax and T. congolense was (1.0%) and no mixed infection of trypanosomes, SGHV and Wolbachia was detected.

Conclusion

The results indicated a high rate of trypanosome infection in tsetse wild populations in West African countries but lower infection rate of both Wolbachia and SGHV. Double or triple mixed trypanosome infections were found. In addition, mixed trypanosome and SGHV infections existed however no mixed infections of trypanosome and/or SGHV with Wolbachia were found.

     

Agrobacterium strain specificity and shooty tumour formation in eucalypt (Eucalyptus grandis ×E. urophylla)

Summary To develop a successful protocol forAgrobacterium-mediated transformation in plants it is essential to determine the most efficient bacterial strain/plant genotype interaction. In the present work, we evaluated the susceptibility ofEucalyptus grandis ×E. urophylla to fiveAgrobacterium rhizogenes and twelveA. tumefaciens wildtype strains. The results showed different degrees of virulence, according to the strain tested, indicating that transformation of this eucalypt hybrid by Agrobacterium-derived vectors is possible. All developed tumours showed an autonomous growth when transferred to a hormone-free medium. Some of these tumours formed shoots spontaneously, with a normal phenotype. Polymerase Chain Reaction (PCR) and Southern blot analyses were performed to confirm the absence of the oncogenic T-DNA in plants derived from these shooty tumours.     

Mammalian cell entry (Mce) protein of Leptospira interrogans binds extracellular matrix components,plasminogen and β2 integrin

A severe re‐emergingzoonosis, leptospirosis, is caused by pathogenic spirochetes of the genus Leptospira. Several studies have identified leptospiral surface proteins with the ability to bind ECM and plasma components, which could mediate adhesion and invasion through the hosts. It has been shown that Mce of pathogenic Leptospira spp. is an RGD (Arg‐Gly‐Asp)‐motif‐dependent virulence factor, responsible for infection of cells and animals. In the present article, we decided to further study the repertoire of the Mce activities in leptospiral biological properties. We report that the recombinant Mce is a broad‐spectrum ECM‐binding protein, capable of interacting with laminin, cellular and plasma fibronectin and collagen IV. Dose­–r­esponse interaction was observed for all the components, fulfilling ligand­–receptor requirements. Mce is a PLG binding protein capable to recruit this component from NHS, generating PLA in the presence of PLG activator. Binding of Mce was also observed with the leukocyte cell receptors αLβ2 [(CD11a/CD18)‐LFA‐1] and αMβ2 [(CD11b/CD18)‐Mac‐1], suggesting the involvement of this protein in the host immune response. Indeed, virulent Leptospira L1‐130 was capable of binding both integrins, whereas culture‐attenuated M‐20 strain only bind to αMβ2 [(CD11b/CD18)‐Mac‐1]. To the best of our knowledge, this is the first work to describe that Mce surface protein could mediate the attachment of Leptospira interrogans to human cell receptors αLβ2(CD11a/CD18) and αMβ2(CD11b/CD18).     

Kinetic characterization of a novel acid ectophosphatase from <Emphasis Type="Italic">Enterobacter asburiae</Emphasis>

Expression of acid ectophosphatase by Enterobacter asburiae, isolated from Cattleya walkeriana (Orchidaceae) roots and identified by the 16S rRNA gene sequencing analysis, was strictly regulated by phosphorus ions, with its optimal activity being observed at an inorganic phosphate concentration of 7 mM. At the optimum pH 3.5, intact cells released p-nitrophenol at a rate of 350.76 ± 13.53 nmol of p-nitrophenolate (pNP)/min/10⁸ cells. The membrane-bound enzyme was obtained by centrifugation at 100,000 × g for 1 h at 4°C. p-Nitrophenylphosphate (pNPP) hydrolysis by the enzyme follows “Michaelis-Menten” kinetics with V = 61.2 U/mg and K_0.5 = 60 μM, while ATP hydrolysis showed V = 19.7 U/mg, K_0.5 = 110 μM, and n_H = 1.6 and pyrophosphate hydrolysis showed V = 29.7 U/mg, K_0.5 = 84 μM, and n_H = 2.3. Arsenate and phosphate were competitive inhibitors with Ki = 0.6 mM and K_i = 1.8 mM, respectively. p-Nitrophenyl phosphatase (pNPPase) activity was inhibited by vanadate, while p-hydroxymercuribenzoate, EDTA, calcium, copper, and cobalt had no inhibitory effects. Magnesium ions were stimulatory (K_0.5 = 2.2 mM and n_H = 0.5). Production of an acid ectophosphatase can be a mechanism for the solubilization of mineral phosphates by microorganisms such as Enterobacter asburiae that are versatile in the solubilization of insoluble minerals, which, in turn, increases the availability of nutrients for plants, particularly in soils that are poor in phosphorus.     

The essential gene YMR134W from Saccharomyces cerevisiae is important for appropriate mitochondrial iron utilization and the ergosterol biosynthetic pathway

A thermosensitive strain (YMR134W^ts) of the essential gene YMR134W presented up to 40% less ergosterol, threefold lower oxygen consumption and impaired growth on respiratory conditions. The iron content in the mitochondrial fraction of YMR134W^ts cells was considerably low, despite these cells uptake and accumulate more iron from the culture media than wild-type cells. YMR134W^ts cells were also more susceptible to oxidative stress. The results suggest that Ymr134wp is essential to aerobic growth due to its function in ergosterol biosynthesis, playing a role in maintaining mitochondrial and plasma membrane integrity and consequently impacting the iron homeostasis, respiratory metabolism and antioxidant response.     

2001: A Household Analysis of Huastec Maya Agriculture and Land Use at the Height of the Coffee Crisis

Over the last decade, historically low market prices for Coffea arabica have affected smallholder shade coffee-growing households throughout northern Latin America. In an effort to better understand household response to the coffee crisis and associated landscape changes, this paper examines agricultural production choices and land use patterns among Huastec Maya coffee-growing households. Using data compiled from 47 household interviews, I describe the cultural-geographical landscape in which the Huastec Maya land use system is embedded. In addition, I examine the economics of household production through a financial cost-benefit analysis and through an exploration of the relationship between land availability and land use patterns. Results show that economic inputs and returns from agriculture are highly variable, and that, in 2001, coffee cultivation was not a viable cash-generating strategy for most households. Land availability was found to have a significant effect on land use decisions, especially the proportion of land area devoted to fallow. Most importantly, however, the case study suggests that a purely economic approach does not suffice in explaining why the Huastec Maya continued to grow coffee in 2001, after years of low prices. Household production choices and livelihood strategies must also be viewed within a cultural context.     

Intranasal guanosine administration presents a wide therapeutic time window to reduce brain damage induced by permanent ischemia in rats

In addition to its intracellular roles, the nucleoside guanosine (GUO) also has extracellular effects that identify it as a putative neuromodulator signaling molecule in the central nervous system. Indeed, GUO can modulate glutamatergic neurotransmission, and it can promote neuroprotective effects in animal models involving glutamate neurotoxicity, which is the case in brain ischemia. In the present study, we aimed to investigate a new in vivo GUO administration route (intranasal, IN) to determine putative improvement of GUO neuroprotective effects against an experimental model of permanent focal cerebral ischemia. Initially, we demonstrated that IN [³H] GUO administration reached the brain in a dose-dependent and saturable pattern in as few as 5 min, presenting a higher cerebrospinal GUO level compared with systemic administration. IN GUO treatment started immediately or even 3 h after ischemia onset prevented behavior impairment. The behavior recovery was not correlated to decreased brain infarct volume, but it was correlated to reduced mitochondrial dysfunction in the penumbra area. Therefore, we showed that the IN route is an efficient way to promptly deliver GUO to the CNS and that IN GUO treatment prevented behavioral and brain impairment caused by ischemia in a therapeutically wide time window.