Algistatic effect of a quinonamethide triterpene on Microcystis novacekii

Cyanobacteria proliferation represents a problem to water treatment for human consumption supply. Species of the genus Microcystis, commonly found in continental waters, can bloom and produce microcystine and other toxic compounds associated to human and animal poisoning, depending on the nutrient levels present in the water. The use of natural products to control cyanobacteria blooms is promising since they are less harmful to the environment than compounds obtained by organic syntheses. Triterpenes, which are associated with several biological activities, have been isolated from species of the genus Maytenus (Celastraceae), commonly found in Cerrado regions of Brazil. Tingenone is a pentacyclic triterpene that has cytotoxic properties and induces growth inhibition in some microorganisms. In this study, the effects of tingenone isolated from Maytenus gonoclada at distinct concentrations (e.g., 50, 150, 500, 1,500, and 4,500 μg? L^?1) on the growth rates of Microcystis novacekii was investigated. The algicide activity was verified using M. novacekii cultures growing in ASM1 culture medium at 23 °C and continuous illumination for 96 h. Growth inhibition was monitored by light microscopy and optical density (OD_680 nm). The median effective concentration associated to the M. novacekii inhibition growth induced by tingenone was 12.2 μg? L^?1. The result indicates that tingenone has algicide effect and can be potentially applied in water management for public supply, replacing synthetic algicides.     

Soybean lecithin-based extender as an alternative for goat sperm cryopreservation

The aim of this study was to evaluate the effect of different concentrations of soybean lecithin (SL) in extenders for sperm goat cryopreservation. Sexually mature male Saanen goats (n = 4) were used, and the ejaculates were obtained using an artificial vagina method. The semen samples were pooled and diluted in a skim milk-based extender (control group; CG) or Tris extender supplemented with SL at different concentrations (G1 = 0.04%, SL G2 = 0.08% SL and G3 = 0.16%) for a final concentration of 240 × 10⁶ spermatozoa/mL. The semen samples were packed in straws (0.25 mL), frozen using an automated system and stored in liquid nitrogen (?196 °C). After thawing (37 °C/30 s), the samples were evaluated for sperm quality parameters, including sperm motility, membrane integrity, acrosome integrity and mitochondrial activity. No significant difference was observed among the experimental and control groups for all of the parameters (P > 0.05). However, even though the control group presented a significantly lower mitochondrial membrane potential compared to fresh semen (P < 0.05), the same did not occur for the extender supplemented with soybean lecithin, that is, it did not differ from fresh sperm (P > 0.05). The extender containing soybean lecithin at different concentrations preserved the sperm quality parameters in a manner similar to the conventional skim milk-based extender. Thus, it is concluded that an extender containing soybean lecithin as the lipoprotein source can be used for freezing goat semen.     

Influence of seasonal variation on the phenology and liriodenine content of Annona lutescens (Annonaceae)

Annona lutescens Saff. (Annonaceae) grows as a native tree in Chiapas, Mexico in Tropical Dry Forest habitat. Like most Annonaceae, it biosynthesizes benzylisoquinoline alkaloids, mostly liriodenine. To determine the influence of seasonal changes in the accumulation of liriodenine, the monthly variation of liriodenine content in roots, stems and leaves of mature and young trees was observed. These parts of young and mature A. lutescens trees were collected monthly over a 1 year period and the alkaloids were extracted; the liriodenine was quantified by high-resolution liquid chromatography. The phenological stages of the species were also assessed (leaf development, flowering and fruiting) using the Biologische Bundesanstalt, Bundessortenamt und Chemische Industrie (BBCH) scale. The analysis of both young and mature trees showed a significant increase in the liriodenine concentration occurs within roots during the dry season, which coincides with leaf fall. A significant decrease also occurred at the beginning of the rainy season (the period of leaf growth); the liriodenine content for the next rainy season did not reach the levels of the previous dry season. The climatic variation induced phenological and physiological changes in this species.     

Diurnal Variation of Plasmatic Melatonin,Corticosterone and Variation of General Activity in Pigeons under Light-Dark Cycle and Constant Light

This work analyzed the diurnal variation of general activity and plasmatic levels of melatonin and corticosterone in pigeons submitted to a 12:00:12:00 h light-dark cycle (lights on at 6:00 a.m.) or to constant light. In both conditions pigeons were observed in 5-min sessions at times 03:00, 06:00, 09:00, 12:00, 15:00, 18:00, 21:00 and 24:00 h during two successive days. Behavior was video taped in the home cages for posterior categorization and quantification. Radioimmunoassays were used to evaluate plasmatic levels of melatonin and corticosterone. Blood samples were obtained at the times of behavioral observation. In the light-dark condition the results showed day-night variation of general activity (p &lt; 0.001) and a robust diurnal rhythm of plasmatic melatonin (p &lt; 0.001). Both of these variations as well as the oscillatory secretion of corticosterone disappeared under constant light condition. The parallel changes in general activity and blunting of melatonin rhythm secretion in constant light condition agree with previous evidences that melatonin may regulate behavioral oscillations in the pigeon. The present data are related to the proposition that the timing system in pigeons may involve neuroendocrine relations characterized by interactions between blood born signalization by melatonin and corticosterone.     

Circaseptan Rhythms of Semen Characteristics of a Brazilian Breed (“Mangalarga”) Stallion

We describe the semen characteristics of a 21-year old “mangalarga” stallion living under natural temperature and photoperiod conditions in São José do Rio Pardo, São Paulo, Brazil (latitude 21°36' S; longitude 46°53' W). The horse fed on natural pasture and a nutritionally balanced feed twice a day (11:00 and 17:00 h). Water and a mineral supplement were available “ad libitum”. Semen was collected for over 36 months (Oct 89-Dec 92) almost daily between 08:00 and 10:00 h by an artificial vagina and evaluated for volume of ejaculate, spermatozoa motility and concentration by standard procedures. Analysis of data from a total of 128-days was performed according to the Fast Fourier Transform Technique (FFT). Statistically significant periods of 7-day were demonstrated for volume, motility, and spermatozoa concentration. Circaseptan rhythms and, particularly, the circannual rhythm (already described in a previous publication) are probably related to ecological diversity and reproductive strategies.     

Temperature alters interspecific relationships among aquatic fungi

Temperature is a key factor in determining the structure and performance of fungal assemblages on decomposing plant litter in streams. However, little is known of how temperature affects interspecific relationships among fungi. We compared the growth of four aquatic hyphomycetes co-occurring in temperate streams, in monocultures and all species combinations when exposed to five temperatures from 11 to 27 °C. In monocultures, maximum growth rates of Heliscus submersus, Lunulospora curvula and Varicosporium elodeae occurred at 27 °C whereas Articulospora tetracladia had the lowest growth rate. At 27 °C, the increase in species diversity had no effect on the growth of V. elodeae, increased the growth of H. submersus and L. curvula, and decreased the growth of A. tetracladia. Results suggest that within a species' optimal temperature range the growth of that species increases with higher fungal diversity, while outside this range growth decreases with diversity.     

Potential role of oxidative exoenzymes of the extremophilic fungus Pestalotiopsis palmarum BM-04 in biotransformation of extra-heavy crude oil

Large amount of drilling waste associated with the expansion of the Orinoco Oil Belt (OOB), the biggest proven reserve of extra-heavy crude oil (EHCO) worldwide, is usually impregnated with EHCO and highly salinized water-based drilling fluids. Oxidative exoenzymes (OE) of the lignin-degrading enzyme system (LDS) of fungi catalyse the oxidation of a wide range of toxic pollutants. However, very little evidences on fungal degradation or biotransformation of EHCO have been reported, which contain high amounts of asphaltenes and its biodegradation rate is very limited. The aims of this work were to study the ability of Pestalotiopsis palmarum BM-04 to synthesize OE, its potential to biotransform EHCO and to survive in extreme environmental conditions. Enzymatic studies of the LDS showed the ability of this fungus to overproduce high amounts of laccase (LACp) in presence of wheat bran or lignin peroxidase (LIPp) with EHCO as sole carbon and energy source (1300 U mgP⁻¹ in both cases). FT-IR spectroscopy with Attenuated Total Reflectance (ATR) analysis showed the enzymatic oxidation of carbon and sulfur atoms in both maltenes and asphaltenes fractions of biotreated EHCO catalysed by cell-free laccase-enriched OE using wheat bran as inducer. UV-visible spectrophotometry analysis revealed the oxidation of the petroporphyrins in the asphaltenes fraction of biotreated EHCO. Tolerance assays showed the ability of this fungus to grow up to 50 000 p.p.m. of EHCO and 2000 mM of NaCl. These results suggest that P. palmarum BM-04 is a hopeful alternative to be used in remediation processes in extreme environmental conditions of salinity and EHCO contamination, such as the drilling waste from the OOB.     

Nosocomial Bloodstream Infections in Brazilian Pediatric Patients: Microbiology,Epidemiology, and Clinical Features

Background

Nosocomial bloodstream infections (nBSIs) are an important cause of morbidity and mortality and are the most frequent type of nosocomial infection in pediatric patients.

Methods

We identified the predominant pathogens and antimicrobial susceptibilities of nosocomial bloodstream isolates in pediatric patients (≤16 years of age) in the Brazilian Prospective Surveillance for nBSIs at 16 hospitals from 12 June 2007 to 31 March 2010 (Br SCOPE project).

Results

In our study a total of 2,563 cases of nBSI were reported by hospitals participating in the Br SCOPE project. Among these, 342 clinically significant episodes of BSI were identified in pediatric patients (≤16 years of age). Ninety-six percent of BSIs were monomicrobial. Gram-negative organisms caused 49.0% of these BSIs, Gram-positive organisms caused 42.6%, and fungi caused 8.4%. The most common pathogens were Coagulase-negative staphylococci (CoNS) (21.3%), Klebsiella spp. (15.7%), Staphylococcus aureus (10.6%), and Acinetobacter spp. (9.2%). The crude mortality was 21.6% (74 of 342). Forty-five percent of nBSIs occurred in a pediatric or neonatal intensive-care unit (ICU). The most frequent underlying conditions were malignancy, in 95 patients (27.8%). Among the potential factors predisposing patients to BSI, central venous catheters were the most frequent (66.4%). Methicillin resistance was detected in 37 S. aureus isolates (27.1%). Of the Klebsiella spp. isolates, 43.2% were resistant to ceftriaxone. Of the Acinetobacter spp. and Pseudomonas aeruginosa isolates, 42.9% and 21.4%, respectively, were resistant to imipenem.

Conclusions

In our multicenter study, we found a high mortality and a large proportion of gram-negative bacilli with elevated levels of resistance in pediatric patients.     

Associations between dru Types and SCCmec Cassettes

Molecular typing is an important tool in the investigation of methicillin resistant Staphylococcus aureus (MRSA) outbreaks and in following the evolution of MRSA. The staphylococcal cassette chromosome mec (SCCmec) contains a hypervariable region with a variable number of 40 bp repeats named direct repeat units (dru). The dru region has been suggested as a supplementary typing method for MRSA and an international nomenclature exists. The purpose of this study was to investigate the diversity and variability of the dru region in a diverse collection of MRSA. We studied 302 MRSA isolates harbouring SCCmec types I to VI. The isolates represented a broad genetic background based on Staphylococcal protein A (spa) typing and multilocus sequence typing (MLST) and included 68 isolates (68 patients) from an outbreak with t024-ST8-IVa and 26 isolates from the same patient. Sequencing identified 53 dru types (dt) in 283 isolates, while eighteen isolates contained no dru repeats and one isolate resisted sequencing. The most common dru type, dt10a, was present in 53% of the sequenced isolates and was found in all SCCmec types, except type II. Seven (10%) of the 68 epidemiologically related patients had isolates with dru type variants indicating that dru typing is not useful as a first line epidemiological typing tool. However, MRSA isolates cultured from a single patient over a three year period exhibited a single dru type. The finding of dt10a in most SCCmec types suggests that dru and mecA originate from the same Staphylococcus species.     

Ocean Acidification Disrupts Prey Responses to Predator Cues but Not Net Prey Shell Growth in Concholepas concholepas (loco)

Background

Most research on Ocean Acidification (OA) has largely focused on the process of calcification and the physiological trade-offs employed by calcifying organisms to support the building of calcium carbonate structures. However, there is growing evidence that OA can also impact upon other key biological processes such as survival, growth and behaviour. On wave-swept rocky shores the ability of gastropods to self-right after dislodgement, and rapidly return to normal orientation, reduces the risk of predation.

Methodology/Principal Findings

The impacts of OA on this self-righting behaviour and other important parameters such as growth, survival, shell dissolution and shell deposition in Concholepas concholepas (loco) were investigated under contrasting pCO₂ levels. Although no impacts of OA on either growth or net shell calcification were found, the results did show that OA can significantly affect self-righting behaviour during the early ontogeny of this species with significantly faster righting times recorded for individuals of C. concholepas reared under increased average pCO₂ concentrations (± SE) (716±12 and 1036±14 µatm CO₂) compared to those reared at concentrations equivalent to those presently found in the surface ocean (388±8 µatm CO₂). When loco were also exposed to the predatory crab Acanthocyclus hassleri, righting times were again increased by exposure to elevated CO₂, although self-righting times were generally twice as fast as those observed in the absence of the crab.

Conclusions and Significance

These results suggest that self-righting in the early ontogeny of C. concholepas will be positively affected by pCO₂ levels expected by the end of the 21st century and beginning of the next one. However, as the rate of self-righting is an adaptive trait evolved to reduce lethal predatory attacks, our result also suggest that OA may disrupt prey responses to predators in nature.