Progress in understanding the vulnerability of freshwater ecosystems.

The ability to collect and synthesize long-term environmental monitoring data is essential for the effective management of freshwater ecosystems. Progress has been made in assessment and monitoring approaches that have integrated routine monitoring programs into more holistic watershed-scale vulnerability assessments. While the concept of vulnerability assessment is well-defined for ecosystems, complementary and sometimes competing concepts of adaptive management, ecological integrity, and ecological condition complicate the communication of results to a broader audience. Here, we identify progress in freshwater assessments that can contribute to the identification and communication of freshwater vulnerability. We review novel methods that address common challenges associated with: 1) a lack of baseline information, 2) variability associated with a spatial context, and 3) the taxonomic sufficiency of biological indicators used to make inferences about ecological conditions. Innovation in methods and communication are discussed as a means to highlight meaningful cost-effective results that target policy towards heuristic ecosystem-management.

Assessment of ecological impairment of Arctic streams: Challenges and future directions.

As increased growth and development put pressure on freshwater systems in Arctic environments, there is a need to maintain a meaningful and feasible framework for monitoring water quality. A useful tool for monitoring the ecological health of aquatic systems is by means of the analysis and inferences made from benthic invertebrates in a biomonitoring approach. Biomonitoring of rivers and streams within the Arctic has been under-represented in research efforts. Here, we investigate an approach for monitoring biological impairment in Arctic streams from anthropogenic land use at two streams with different exposure to urban development in Iqaluit, Nunavut, Arctic Canada. Sites upstream of development, at midpoint locations, and at the mouth of each waterbody were sampled during 6 campaigns (2008, 2009, 2014, 2015, 2018, and 2019) to address spatial and temporal variability of the macroinvertebrate community. The influence of taxonomic resolution scaling was also examined in order to understand the sensitivity of macroinvertebrates as indicators in Arctic aquatic systems. We demonstrate that standard biological metrics were effective in indicating biological impairment downstream of sources of point-source pollutants. A mixed-design ANOVA for repeated measures also found strong interannual variability; however, we did not detect intra-annual variation from seasonal factors. When examining metrics at the highest taxonomic resolution possible, the sensitivity of metrics increased. Likewise, when trait-based metrics (α functional diversity) were applied to indicators identified at high taxonomic resolution, a significant difference was found between reference and impacted sites. Our results show that even though Arctic systems have lower diversity and constrained life-history characteristics compared to temperate ecosystems, biomonitoring is not only possible, but also equally effective in detecting trends from anthropogenic activities. Thus, biomonitoring approaches in Arctic environments are likely a useful means for providing rapid and cost-effective means of assessing future environmental impact.

Biomass burning and carbon monoxide patterns in Brazil during the extreme drought years of 2005, 2010, and 2015.

In the 21st century, severe droughts associated with climate change will increase biomass burning (BB) in Brazil caused by the human activities. Recent droughts, especially in 2005, 2010, and 2015, caused strong socioeconomic and environmental impacts. The 2015 drought considered the most severe since 1901, surpassed the 2005 and 2010 events in respect to area and duration. Herein, based on satellite data, the 2005, 2010 and 2015 drought impacts on wildfire episodes and carbon monoxide (CO) variability during the dry and the dry-to-wet transition seasons were examined. The BB occurrences in the dry season were fewer during 2015 than during 2005 (-44%) and 2010 (-47%). Contrasting, the BB events in the dry-to-wet transition season, were higher during 2015 than during 2005 (+192%) and 2010 (+332%). The BB outbreaks were concentrated in the southern and southwestern Amazon during 2005, in the Cerrado region during 2010, and mainly in the central and northern Amazon during 2015, an area normally with few fires. The CO concentration showed positive variations (up to +30%) occurred in the southern Amazon and central Brazil during the 2005 and 2010 dry seasons, and north of 20 °S during the 2015-2016 dry-to-wet transition season. The BB outbreaks and the CO emissions showed a considerable spatiotemporal variability among the droughts of 2005, 2010, and 2016, first of them driven by local conditions in the tropical North Atlantic (TNA), characterized by warm than normal sea surface waters and the other two by the El Niño occurrences.

Amides as cryoprotectants for freezing stallion semen: a review.

Stallion semen cryopreservation, despite its impact on the horse industry, is not an established technology. During the last years, a number of modifications have been proposed to the freezing process, however, a large population of stallions still have poor semen quality and fertility after frozen-thawed. Glycerol toxicity could be a reason for the variation on stallion sperm freezability. There are limited publications concerning the use of alternative cryoprotectants for equine sperm. Glycerol is contraceptive for some species and other cryoprotectors, such as amides, have been show to be a good option for freezing semen of these species. Recent reports have shown encouraging data respecting the use of amides as cryoprotectants for stallions, with more remarkable improvements for semen from stallions that freeze poorly when glycerol is used.

DNA repair in Chromobacterium violaceum

Chromobacterium violaceum is a Gram-negative beta-proteobacterium that inhabits a variety of ecosystems in tropical and subtropical regions, including the water and banks of the Negro River in the Brazilian Amazon. This bacterium has been the subject of extensive study over the last three decades, due to its biotechnological properties, including the characteristic violacein pigment, which has antimicrobial and anti-tumoral activities. C. violaceum promotes the solubilization of gold in a mercury-free process, and has been used in the synthesis of homopolyesters suitable for the production of biodegradable polymers. The complete genome sequence of this organism has been completed by the Brazilian National Genome Project Consortium. The aim of our group was to study the DNA repair genes in this organism, due to their importance in the maintenance of genomic integrity. We identified DNA repair genes involved in different pathways in C. violaceum through a similarity search against known sequences deposited in databases. The phylogenetic analyses were done using programs of the PHILYP package. This analysis revealed various metabolic pathways, including photoreactivation, base excision repair, nucleotide excision repair, mismatch repair, recombinational repair, and the SOS system. The similarity between the C. violaceum sequences and those of Neisserie miningitidis and Ralstonia solanacearum was greater than that between the C. violaceum and Escherichia coli sequences. The peculiarities found in the C. violaceum genome were the absence of LexA, some horizontal transfer events and a large number of repair genes involved with alkyl and oxidative DNA damage

Respiratory mechanics and lung histology in normal rats anesthetized with sevoflurane.

Respiratory system, lung, and chest wall mechanical properties were subdivided into their resistive, elastic, and viscoelastic/inhomogeneous components in normal rats, to define the sites of action of sevoflurane. In addition, we aimed to determine the extent to which pretreatment with atropine modified these parameters. Twenty-four rats were divided into four groups of six animals each: in the P group, rats were sedated (diazepam) and anesthetized with pentobarbital sodium; in the S group, sevoflurane was administered; in the AP and AS groups, atropine was injected 20 min before sedation/anesthesia with pentobarbital and sevoflurane, respectively. Sevoflurane increased lung viscoelastic/inhomogeneous pressures and static elastance compared with rats belonging to the P group. In AS rats, lung static elastance increased in relation to the AP group. In conclusion, sevoflurane anesthesia acted not at the airway level but at the lung periphery, stiffening lung tissues and increasing mechanical inhomogeneities. These findings were supported by the histological demonstration of increased areas of alveolar collapse and hyperinflation. The pretreatment with atropine reduced central and peripheral airway secretion, thus lessening lung inhomogeneities.

Prevalence of intranasal ectopic teeth in children with complete unilateral and bilateral cleft lip and palate.

OBJECTIVE: The objective of this study was to determine the prevalence of ectopic eruption of intranasal teeth. DESIGN: This was a retrospective study, where records of children with repaired cleft lip and palate were analyzed. SETTING: The study was conducted at a large craniofacial center, the Hospital for Rehabilitation of Craniofacial Anomalies, USP, Bauru, São Paulo, Brazil. SUBJECTS: The sample consisted of 815 records from patients with bilateral cleft lip and palate (BCLP) and 1,495 records from patients with unilateral cleft lip and palate (UCLP). The age of the subjects was 5 to 10 years old and the groups included both males and females. RESULTS: The results showed that 0.61% of the children with BCLP and 0.40% of those with UCLP had an intranasal tooth. The prevalence of an intranasal tooth for the whole group was 0.48%, and it appeared to be more common in females.

Effects of halothane on respiratory mechanics and lung histopathology in normal rats.

It is generally accepted that halothane reduces airway and tissue resistance in lungs with preexisting airway tone. However, under conditions of resting airway tone, pulmonary resistance remains unaltered. In this study, we have determined the effects of halothane on respiratory system, pulmonary and chest wall resistive, elastic and viscoelastic mechanical properties, and related the results to findings from lung histology in intact normal rats. Sixteen adult male Wistar rats were allocated randomly to one of two groups (n = 8 in each group): control or halothane group. In the control group, animals were sedated with diazepam 5 mg i.p. and anaesthetized with pentobarbital 20 mg kg-1 i.p. In the halothane group, the anaesthetic was administered at an end-tidal concentration of I MAC throughout the study. Rats were paralysed and underwent mechanical ventilation. Halothane decreased airway resistance but increased the tissue component of resistance (caused by viscoelastic elements and lung inhomogeneity). Static and dynamic elastance also increased with halothane anaesthesia. Pulmonary resistance remained unchanged. Lung histopathology demonstrated airway dilatation and a greater degree of lung collapse and hyperinflation in the halothane group. We conclude that halothane anaesthesia acts both on airway and lung tissue. In airway tissue, dilatation occurs but the lung periphery stiffens. Consequently, these opposing effects result in no overall apparent change in mechanical properties, although changes are observed during halothane anaesthesia in normal animal and subjects.

Pulmonary morphofunctional effects of acute myocardial infarction.

Acute myocardial infarction (AMI) may yield several respiratory changes. Nevertheless, no comprehensive pulmonary morphological/physiological correlation has been performed under this condition. The aims of the present investigation were: 1) to determine the respiratory parameters in an experimental model of coronary artery occlusion, 2) to relate these results to findings from lung histopathology, and 3) to evaluate the effects of propranolol used prior to AMI. Twenty-eight rats were anaesthetized and mechanically ventilated. In the control group (C), a suture line was passed around the left anterior descending coronary artery (LADCA). The infarct group (I) was similarly prepared but the LADCA was ligated and infarct resulted. In the control/propranolol (CP) and infarct/propranolol (IP) groups, propranolol was intravenously injected 5 min before surgery as performed in groups C and I, respectively. Lung static (EL,st) and dynamic (EL,dyn) elastances, airway resistance (RL,int), and viscoelastic/inhomogeneous pressure (deltaP2L) were determined before and 30, 60 and 120 min after surgery. In group I, EL,st, EL,dyn, RL,int and deltaP2L increased progressively throughout the experiment, and were higher than those found in groups C, CP and IP. All respiratory parameters but EL,st remained unaltered in group IP. Lung histopathological examination demonstrated alveolar, interstitial and intrabronchial oedema in group I. Group IP showed only interstitial oedema. Acute myocardial infarction yields lung resistive, elastic and viscoelastic changes. The last two results from alveolar and interstitial oedema, respectively. The previous use of propranolol diminishes respiratory changes.

Effects of prosthetic reconstruction of the abdominal wall on respiratory mechanics in rats.

Respiratory mechanics and thoracoabdominal morphometry were determined in four sets of animal experiments before and after surgery. In group RRA the rectus abdominus muscles were removed; in RRAH rats the muscle resection was followed by lung hyperinflation; in PPM animals the defect was repaired by suturing a polypropylene mesh (Marlex); and in PPMH lung hyperinflation was performed after abdominal wall reconstruction. Lung and chest wall elastances, and chest wall viscoelastic/inhomogeneous pressures increased in RRA, RRAH and PPM groups. Static lung elastance was progressively smaller in the following order: RRA, PPM, and PPMH. In conclusion, removal of the rectus abdominus muscles and abdominal wall reconstruction could account for higher energy losses against viscoelastic and elastic forces acting on the chest wall, and these are related to a cephalad deviation of the diaphragm. Furthermore, hyperinflation reverses lung elastic modification after abdominal wall reconstruction with PPM, without beneficial effects in the presence of abdominal wall defect.