Assemblage structure and dynamics of terrestrial birds in the southwest Amazon: a camera‐trap case study

Habitat spatial distribution, seasonal variation, and activity patterns influence changes in vertebrate assemblages over time. Terrestrial birds play major roles in the dynamics of tropical forests, but there are few effective methods to study these species due to their cryptic coloration and elusive behavior. We used camera‐trap data collected during 16 mo (February 2017–June 2018) to describe the terrestrial avifauna in southeastern Peru, assess to what extent the composition of terrestrial avifauna changes among seasons and across two major habitats (terra firme and floodplain forests), and determine daily activity patterns of terrestrial birds. We used overlap analyses to examine temporal co‐occurrence between ecologically similar and sympatric species. Camera traps recorded 16 species, including eight species in the family Tinamidae. Capture rates were highest for Pale‐winged Trumpeters (Psophia leucoptera; Psophiidae) and Gray‐fronted Doves (Leptolila rufaxilla; Columbidae). Species composition did not differ between habitats or seasons, and capture rates between habitats only differed for White‐throated Tinamous (Tinamus guttatus). Overlaps of activity patterns were high between ecologically similar species and species found in terra firme habitats (White‐throated Tinamous and Cinereous Tinamous, Crypturellus cinereus) and in both habitat types (Pale‐winged Trumpeters and Gray‐fronted Doves). Low numbers of captures of possibly locally rare or less abundant species hindered a complete analysis of spatial and seasonal patterns of terrestrial bird assemblages. We suggest a greater sampling effort and greater spatial replication to better understand the spatial and seasonal dynamics of the terrestrial avifauna. Further studies that assess the mechanisms that allow the coexistence of sympatric tinamous would be valuable, both in our study area and elsewhere. The use of camera traps in long‐term monitoring projects proved to be an effective tool for monitoring terrestrial birds, identifying cryptic and often rare animals to species level, and providing valuable ecological information at species and community levels.     

Automated audio recording as a means of surveying tinamous (Tinamidae) in the Peruvian Amazon

1. The use of machine learning technologies to process large quantities of remotely collected audio data is a powerful emerging research tool in ecology and conservation.
2. We applied these methods to a field study of tinamou (Tinamidae) biology in Madre de Dios, Peru, a region expected to have high levels of interspecies competition and niche partitioning as a result of high tinamou alpha diversity. We used autonomous recording units to gather environmental audio over a period of several months at lowland rainforest sites in the Los Amigos Conservation Concession and developed a Convolutional Neural Network‐based data processing pipeline to detect tinamou vocalizations in the dataset.
3. The classified acoustic event data are comparable to similar metrics derived from an ongoing camera trapping survey at the same site, and it should be possible to combine the two datasets for future explorations of the target species'' niche space parameters.
4. Here, we provide an overview of the methodology used in the data collection and processing pipeline, offer general suggestions for processing large amounts of environmental audio data, and demonstrate how data collected in this manner can be used to answer questions about bird biology.

     

Halting ionic shuttle to disrupt the synthetic machinery—Structural and molecular insights into the inhibitory roles of Bedaquiline towards Mycobacterium tuberculosis ATP synthase in the treatment of tuberculosis

Therapeutic targeting of the adenosine triphosphate (ATP) machinery of Mycobacterium tuberculosis (Mtb) has recently presented a potent and alternative measure to halt the pathogenesis of tuberculosis. This has been potentiated by the development of bedaquiline (BDQ), a novel small molecule inhibitor that selectively inhibits mycobacterial F₁F_o-ATP synthase by targeting its rotor c-ring, resulting in the disruption of ATP synthesis and consequential cell death. Although the structural resolution of the mycobacterial C₉ ring in co`mplex with BDQ provided the first-hand detail of BDQ interaction at the c-ring region of the ATP synthase, there still remains a need to obtain essential and dynamic insights into the mechanistic activity of this drug molecule towards crucial survival machinery of Mtb. As such, for the first time, we report an atomistic model to describe the structural dynamics that explicate the experimentally reported antagonistic features of BDQ in halting ion shuttling by the mycobacterial c-ring, using molecular dynamics simulation and the Molecular Mechanics/Poisson-Boltzmann Surface Area methods. Results showed that BDQ exhibited a considerably high ΔG while it specifically maintained high-affinity interactions with Glu65_B and Asp32_B, blocking their crucial roles in proton binding and shuttling, which is required for ATP synthesis. Moreover, the bulky nature of BDQ induced a rigid and compact conformation of the rotor c-ring, which impedes the essential rotatory motion that drives ion exchange and shuttling. In addition, the binding affinity of a BDQ molecule was considerably increased by the complementary binding of another BDQ molecule, which indicates that an increase in BDQ molecule enhances inhibitory potency against Mtb ATP synthase. Taken together, findings provide atomistic perspectives into the inhibitory mechanisms of BDQ coupled with insights that could enhance the structure-based design of novel ATP synthase inhibitors towards the treatment of tuberculosis.     

Enantioselectivity in the metabolism of mexiletine by conjugation in female patients with the arrhythmic form of chronic Chagas' heart disease

The phenomenon of enantioselectivity in the metabolism of mexiletine (MEX) conjugation was investigated in eight female patients with the arrhythmic form of chronic Chagas' heart disease treated with racemic mexiletine hydrochloride (two 100 mg capsules every 8 hr). Blood samples were collected up to 24 hr after the administration of the morning dose, with discontinuation of the subsequent doses during the study period. Plasma concentrations of N‐hydroxymexiletine glucuronide were calculated as the difference between the concentrations of unchanged and total (unchanged + conjugated) MEX enantiomers. Total plasma MEX concentrations were analyzed by HPLC after enzymatic hydrolysis with β‐glucuronidase, the formation of diastereomeric derivatives with the chiral reagent N‐acetyl‐l ‐cysteine/o‐phthalaldehyde, and fluorescence detection. The differences in the pharmacokinetic parameters of the enantiomers were evaluated by the paired t‐test. The plasma concentrations of the (+)‐(S)‐MEX did not differ before and after enzymatic hydrolysis. The pharmacokinetic parameters calculated for (−)‐(R)‐N‐hydroxymexiletine glucuronide are presented as means (95% confidence interval): maximum plasma concentration C_max = 194.0 ng · ml⁻¹ (154.3–233.7), time to maximum plasma concentration t_max = 1.4 hr (0.3–2.5), area under the plasma concentration versus time curve AUC^0–24 = 2099.2 ng · h · ml⁻¹ (1585.6–2612.6), elimination half‐life t_1/2β = 12.8 hr (9.9–15.6) and extent of conjugation of 31.6% (24.3–38.9%). The present data indicate stereospecific conjugation of (−)‐(R)‐N‐hydroxymexiletine in the female patients with the arrhythmic form of Chagas' heart disease. Chirality 11:29–32, 1999. © 1999 Wiley‐Liss, Inc.     

Purification and Characterization of the Lectin from Taro (Colocasia esculenta) and Its Effect on Mouse Splenocyte Proliferation In Vitro and In Vivo

Lectins are proteins found in a wide range of organisms, with the ability to bind reversibly to specific carbohydrates. They can display important biological activities, such as the activation of the cell cycle in lymphocytes. Storage proteins with lectin activity have been reported in tuberous plant species, such as Colocasia esculenta, popularly known as taro. A simple strategy based on Cibacron Blue chromatography was used to purify a 12 kDa polypeptide 1.3-fold, with a recovery of 30 %. The purified protein was identified as tarin by mass spectrometry, which indicated that it was present in G1a/G1d isoforms. Tarin exhibited both agglutinating activity against hamster erythrocytes and mitogenic activity in vitro and in vivo toward mouse splenocytes. Optimum cellular proliferation in vitro was achieved by 625 ng of the crude extract or 500 ng of the purified tarin. Total mouse splenocyte proliferation measured after 5 days of intraperitoneal inoculation of purified tarin was increased 3.3-fold in comparison to the control group. Half of the proliferating cells were identified as B lymphocytes by flow cytometry. These results show that this is an efficient and simple strategy to purify tarin and aid in establishing this protein as a new therapeutic drug, able to promote cell proliferation in a murine model.     

Morphological Characters Useful for the Delimitation of Taxa Within Viola Subsect. Viola (Violaceae): A Morphometric Study from the West Carpathians

Forty-nine morphological characters were scored or measured on 44 populations (376 individuals) of Viola subsect. Viola from the West Carpathians and adjacent areas (Slovakia, Czech Republic, Austria and Hungary). The presence of six species, namely V. alba (represented by subsp. alba), V. ambigua, V. collina, V. hirta, V. odorata and V. suavis s.l. was revealed based on pollen fertility, cytological and morphometric analyses. The morphological characters traditionally used to delimit taxa within the subsection and those revealed by our study as most reliable are widely discussed. A key for identifying the taxa and most common hybrids of subsection Viola occurring in the West Carpathians is presented. Chromosome counting and flow cytometry were used to determine the ploidy levels of the populations studied. All individuals of V. alba subsp. alba, V. collina, V. hirta and V. odorata were tetraploid, while those of V. ambigua and V. suavis s.l. were octoploid.     

Enantioselective analysis of N‐hydroxymexiletine glucuronide in human plasma for pharmacokinetic studies

Enzymatic hydrolysis with β‐glucuronidase/sulfatase was used for the enantioselective determination of N‐hydroxymexiletine glucuronide in plasma for pharmacokinetic studies. N‐Hydroxymexiletine glucuronide was determined as the quantity of mexiletine released by hydrolysis (difference between the enantiomeric concentrations of mexiletine obtained with and without hydrolysis). Plasma samples (100 μl) were treated at pH 5.0 with 10 mg of the enzyme (Limpet Acetone Powder type I) for 16 hr at 37°C and extracted at pH 10.4 with diisopropyl ether. Chiral mexiletine discrimination was obtained by reaction with o‐phthalaldehyde/N‐acetyl‐L ‐cysteine, separation of the resulting diastereomers on a C‐18 reversed‐phase column with a mobile phase of methanol–0.05 N acetate buffer, pH 5.5 (6.5:3.5, v/v), and fluorescence detection (λ_ex 350 nm, λ_em 455 nm). The performance characteristics for the enantioselective analysis of mexiletine preceded by enzymatic hydrolysis were recovery ∼90%, quantification limit 1 ng/ml, and linearity up to 1000 ng/ml plasma for both enantiomers. The coefficients of variation obtained in the study of intra‐ and inter‐day precision were respectively 5% and 7% for both enantiomers. The assay was shown to be suitable for a pharmacokinetic study performed in a patient with the arrhythmic form of chronic Chagas' heart disease treated with 200 mg t.i.d. of racemic mexiletine hydrochloride. The high sensitivity of the method allows analysis of only 100 μl plasma. Chirality 11:85–90, 1999. © 1999 Wiley‐Liss, Inc.     

Enantioselective determination of the hydroxylated metabolites of mexiletine in human plasma

Pre-column derivatization with o-phthaldialdehyde and N-acetyl-l-cysteine was used for liquid-chromatographic diastereomeric resolution of p-hydroxymexiletine (PHM) and hydroxymethylmexiletine (HMM), metabolites of mexiletine formed by aromatic and aliphatic hydroxylation, respectively. The resulting diastereomeric derivatives were resolved on a C₁₈ column and monitored by fluorescence detection. The diastereomeric elution order for both metabolites was determined on the basis of the circular dichroism spectra of each eluted fraction. Plasma samples (500 μl) showed recoveries greater than 75% for both the metabolites. Calibration curves in plasma samples were linear over the concentration ranges 10–500 and 20–1,000 ng/ml for each enantiomer of PHM and HMM, respectively. The limits of quantitation were found to be 10.0 and 5.0 ng/ml for both enantiomers of PHM and HMM. The within-day and between-day coefficients of variation were less than 10%. The assay was shown to be suitable for a pharmacokinetic study performed in a patient with ventricular arrhythmias following the short-term oral treatment of 200 mg t.i.d. of racemic mexiletine hydrochloride. Chirality 9:732–738, 1997. © 1997 Wiley-Liss, Inc.     

Associations of religious and existential variables with psychosocial factors and biomarkers of cardiovascular risk in bereavement

Bereavement increases in prevalence as people age and is associated with multiple psychological and health risks, including cardiovascular risk. Religious and existential variables may play an important role in the health impacts of bereavement. Theorized pathways linking religious and existential variables with health have suggested these associations are due to intermediary psychosocial variables, but have not been tested in bereavement. This research empirically tested these pathways in a bereaved population. In N = 73 adults within 1 year of bereavement (mean age = 64.36), this study examined associations between (1) religious and existential characteristics (religious and spiritual struggles, intrinsic religiosity, and existential quest) and intermediary psychosocial variables (depression, loneliness, and difficulties in emotion regulation), and between (2) intermediary psychosocial variables and bereavement-relevant health outcomes (self-reported health, change in health since last year, grief severity, and cardiovascular biomarkers). Cardiovascular biomarkers (heart rate, heart rate variability, and blood pressure) were collected before, during, and after a laboratory grief recall emotion elicitation. Anticipated associations between self-reported religious and existential characteristics and intermediary variables, and between intermediary variables and self-reported bereavement-relevant outcomes, were consistently observed. However, associations between intermediary variables and cardiovascular biomarkers were largely unobserved. This study examined the role of religious and existential variables in whole-person health after bereavement and is among the first to include biomarkers of cardiovascular risk. Results suggest that although religious and existential variables are associated with important bereavement-related outcomes, these associations may be “skin-deep,” and extensions to cardiovascular functioning should be re-examined.