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.     

Specific Targeting of Caspase-9/PP2A Interaction as Potential New Anti-Cancer Therapy

Purpose

PP2A is a serine/threonine phosphatase critical to physiological processes, including apoptosis. Cell penetrating peptides are molecules that can translocate into cells without causing membrane damage. Our goal was to develop cell-penetrating fusion peptides specifically designed to disrupt the caspase-9/PP2A interaction and evaluate their therapeutic potential in vitro and in vivo.

Experimental Design

We generated a peptide containing a penetrating sequence associated to the interaction motif between human caspase-9 and PP2A (DPT-C9h), in order to target their association. Using tumour cell lines, primary human cells and primary human breast cancer (BC) xenografts, we investigated the capacity of DPT-C9h to provoke apoptosis in vitro and inhibition of tumour growth (TGI) in vivo. DPT-C9h was intraperitonealy administered at doses from 1 to 25 mg/kg/day for 5 weeks. Relative Tumour Volume (RTV) was calculated.

Results

We demonstrated that DPT-C9h specifically target caspase-9/PP2A interaction in vitro and in vivo and induced caspase-9-dependent apoptosis in cancer cell lines. DPT-C9h also induced significant TGI in BC xenografts models. The mouse-specific peptide DPT-C9 also induced TGI in lung (K-Ras model) and breast cancer (PyMT) models. DPT-C9h has a specific effect on transformed B cells isolated from chronic lymphocytic leukemia patients without any effect on primary healthy cells. Finally, neither toxicity nor immunogenic responses were observed.

Conclusion

Using the cell-penetrating peptides blocking caspase-9/PP2A interactions, we have demonstrated that DPT-C9h had a strong therapeutic effect in vitro and in vivo in mouse models of tumour progression.     

3,5-Bis(benzylidene)-4-piperidones and related N-acyl analogs: A novel cluster of antimalarials targeting the liver stage of Plasmodium falciparum

Drug resistance is a major challenge in antimalarial chemotherapy. In addition, a complete cure of malaria requires intervention at various stages in the development of the parasite within the host. There are only a few antimalarials that target the liver stage of the Plasmodium species which is an essential part of the life cycle of the malarial parasite. We report a series of antimalarial 3,5-bis(benzylidene)-4-piperidones and related N-acyl analogs 1–5, a number of which exhibit potent in vitro growth-inhibiting properties towards drug-sensitive D6 and drug-resistant C235 strains of Plasmodium falciparum as well as inhibiting the liver stage development of the malarial life cycle. The compounds 2b (IC₅₀: 165 ng/mL), 3b (IC₅₀: 186 ng/mL), 5c (IC₅₀: 159 ng/mL) and 5d (IC₅₀: 93.5 ng/mL) emerged as lead molecules that inhibit liver stage Plasmodium berghei and are significantly more potent than chloroquine (IC₅₀: >2000 ng/mL) and mefloquine (IC₅₀: >2000 ng/mL) in this screen. All the compounds that showed potent inhibitory activity against the P. berghei liver stage were nontoxic to human HepG2 liver cells (IC₅₀: >2000 ng/mL). The compounds 5a and 5b exhibit comparable metabolic stability as chloroquine and mefloquine in human plasma and the most potent compound 5d demonstrated suitable permeability characteristics using the MDCK monolayer. These results emphasize the value of 3,5-bis(benzylidene)-4-piperidones as novel antimalarials for further drug development.     

Towards an understanding of the role of intrinsic protein disorder on plant adaptation to environmental challenges

Intrinsic protein disorder is an interesting structural feature where fully functional proteins lack a three-dimensional structure in solution. In this work, we estimated the relative content of intrinsic protein disorder in 96 plant proteomes including monocots and eudicots. In this analysis, we found variation in the relative abundance of intrinsic protein disorder among these major clades; the relative level of disorder is higher in monocots than eudicots. In turn, there is an inverse relationship between the degree of intrinsic protein disorder and protein length, with smaller proteins being more disordered. The relative abundance of amino acids depends on intrinsic disorder and also varies among clades. Within the nucleus, intrinsically disordered proteins are more abundant than ordered proteins. Intrinsically disordered proteins are specialized in regulatory functions, nucleic acid binding, RNA processing, and in response to environmental stimuli. The implications of this on plants’ responses to their environment are discussed.     

Influence of acylation of a Peptide corresponding to the amino-terminal region of endothelial nitric oxide synthase on the interaction with model membranes

Covalent attachment of fatty acids to proteins is a common form of protein modification which has been shown to influence both structure and interaction with membranes. Endothelial nitric oxide synthase (eNOS) is dually acylated by the fatty acids myristate and palmitate. We have synthesized four peptides corresponding to the first 28 amino acids of the N-terminal region of eNOS. Besides the nonacylated eNOS sequence, three additional peptides with different degrees of acylation have been obtained: myristoylated, doubly palmitoylated, and dually myristoylated and doubly palmitoylated. Acylation itself, myristic and/or palmitic, confers the peptide the ability to adopt extended conformations, indicated by the fact that the CD spectrum of all acylated peptides has a minimum at approximately 215 nm characteristic of beta-sheet structure. The nonacylated sequence interacts with model membranes composed of acidic phospholipids probably through ionic interactions with the polar headgroup of the phospholipids. However, the acylated peptides are able to insert deeply into the hydrophobic core of both neutral and acidic phospholipids, maintaining the spectral features of extended conformations. When DMPC vesicles containing cholesterol and sphingomyelin at 10% were used, the insertion of the triacylated peptide almost completely canceled the thermal transition, although the interaction of the other acylated peptides also reduced the transition amplitude but to a much lower extent and affected only the acyl chains in the fluid state.     

Tumor necrosis factor regulates intestinal epithelial cell migration by receptor-dependent mechanisms

Altered mucosal integrity andincreased cytokine production, including tumor necrosis factor (TNF),are the hallmarks of inflammatory bowel disease (IBD). In this study,we addressed the role of TNF receptors (TNFR) on intestinal epithelialcell migration in an in vitro wound closure model. With mouse TNFR1 orTNFR2 knockout intestinal epithelial cells, gene transfection, andpharmacological inhibitors, we show a concentration-dependentreceptor-mediated regulation of intestinal cell migration by TNF. Aphysiological TNF level (1 ng/ml) enhances migration through TNFR2,whereas a pathological level (100 ng/ml) inhibits wound closure through TNFR1. Increased rate of wound closure by TNFR2 or inhibition by TNFR1cannot be explained by either increased proliferation orapoptosis, respectively. Furthermore, inhibiting Src tyrosine kinase decreases TNF-induced focal adhesion kinase (FAK) tyrosine phosphorylation and cellular migration. We therefore conclude thatTNFR2 activates a novel Src-regulated pathway involving FAK tyrosinephosphorylation that enhances migration of intestinal epithelial cells.

     

Proteomic identification of brain proteins that interact with dynein light chain LC8

Cytoplasmic dynein is a large minus end-directed microtubule motor that translocates cargos towards the minus end of microtubules. Light chain 8 of the dynein machinery (LC8) has been reported to interact with a large variety of proteins that possess K/RSTQT or GIQVD motifs in their sequence, hence permitting their transport in a retrograde manner. Yeast two-hybrid analysis has revealed that in brain, LC8 associates directly with several proteins such as neuronal nitric oxide synthase, guanylate kinase domain-associated protein and gephyrin. In this work, we report the identification of over 40 polypeptides, by means of a proteomic approach, that interact with LC8 either directly or indirectly. Many of the neuronal proteins that we identified cluster at the post-synaptic terminal, and some of them such as phosphofructokinase, lactate dehydrogenase or aldolase are directly involved in glutamate metabolism. Other pool of proteins identified displayed the LC8 consensus binding motif. Finally, recombinant LC8 was produced and a library of overlapping dodecapeptides (pepscan) was employed to map the LC8 binding site of some of the proteins that were previously identified using the proteomic approach, hence confirming binding to the consensus binding sites.     

Bisphosphoglycerate synthase activity in cells of the erythrocytic line of rat

The specific activity of bisphosphoglycerate synthase (EC 2.7.5.4) is significantly higher in rat mature erythrocytes than in reticulocytes from phenylhydrazine treated animals, while 2,3-bisphosphoglycerate levels do not differ between them. The enzyme specific activity and the concentration of 2,3-bisphosphoglycerate are both negligible in the erythroid cell pool from the bone marrow of anaemic animals. Thus, a cellular specialization in the last stages of erythropoiesis is confirmed. Human bisphosphoglycerate synthase shows a lower specific activity than that of rat without a parallel decrease in 2,3-bisphosphoglycerate levels.