Relationship between cell density and prolidase activity in human skin fibroblasts: effects of ascorbate and fructose

To evaluate the influence of cell density on the activity of fibroblast prolidase (EC 3.4.13.9), we determined this activity in sparse and dense cultures. We also investigated, the effects of different concentrations of β-d(?) fructose and l(+) ascorbate, which both increased cell density at confluency. For a fructose concentration of 25 mM, we observed that in the absence of glucose, intracellular total proteins increased 1.5-fold and prolidase specific activity, 1.8-fold. For ascorbate, a broad optimum concentration was found (range 0.01 – 0.50 mM). Addition to cultures of 0.1 mM ascorbate increased total proteins 1.4-fold, and doubled prolidase activity. This investigation was prompted by our previous results [J. Metab. Dis. 1983, 6, 27–31], confirmed here, and suggesting that increased prolidase activity at confluency was due to a rise in cell density.     

Synthesis,biological evaluation and molecular docking analysis of novel benzopyrimidinone derivatives as potential anti-tyrosinase agents

2-substitued-benzopyrimidinones 2 were synthesized in high to excellent yields in a single step via condensation of 2-aminobenzamide 1 with some aryl-aldehydes in the presence of iodine. Cyclocondensation reaction of hydrazides 3 which were obtained in two steps from benzopyrimidinones 2, with some electrophilic species such as 2,4-pentandione, 2,5-hexandione, 1-phenylbutan-1,3-dione and cyclic anyhdrides provided the new compounds 4a–c, 5a–c, 6a–c, 7a–c, 8a–c and 9a–c. The synthesized compounds were characterized by spectroscopic means. They were also evaluated for their anti-tyrosinase potential. The structure-activity relationship (SAR) was discussed on the basis of the molecular docking analysis.     

Facile synthesis and antimicrobial activity of CdS-Ag2S nanocomposites

In this study CdS-Ag₂S nanocomposites for antibacterial activity were synthesized via facile co-precipitation method using PVP as capping agent. The prepared nanocomposites have particle sizes in the range of 50–100 nm (SEM) and PVP addition has good influence on the morphology of nanocomposites. The antimicrobial activity of pure Ag₂S, CdS and CdS-Ag₂S composites was evaluated against Pseudomonas aeruginosa, Staphylococcus aureus and Escherichia coli. The results demonstrate that antibacterial activity was significantly improved due to increasing ratio of CdS into CdS-Ag₂S nanocomposites in comparison to pure Ag₂S and CdS.     

Studies on the structure of yeast phosphofructokinase

In this paper, we describe an efficient procedure for the purification of yeast phosphofructokinase. This procedure eliminates any time delay and enables to obtain an enzyme with minimum proteolytic alterations. The molecular weights of the oligomeric enzyme and of its constitutive subunits were both evaluated by means of several independent methods. However, the accuracy of each measurement was not sufficient to discriminate between an hexameric and an octameric structure of the enzyme oligomer. On the other hand, crosslinking experiments demonstrated the octameric structure of yeast phosphofructokinase. Obviously, some methods of molecular weight determination have led to erroneous results. In particular, our experiments show that the reliability of molecular weight determinations performed by gel filtration of native proteins must be considered with caution.     

Constitutive behavior of methionyl-tRNA synthetase compared to repressible behavior of methionine adenosyltransferase in mammalian cells

Methionine adenosyltransferase, one of the two major enzymes utilizing methionine, is regulated by the levels of methionine in the growth medium (Jacobsen, S.J., Hoffman, R.M. and Erbe, R.W. (1980) J. Natl. Cancer Inst. 65, 1237–1244, and Caboche, M. and Mulsant, P. (1978) Somatic Cell Genet. 4, 407–421). We report here that methionyl-tRNA synthetase, unlike methionine adenosyltransferase, behaves in a constitutive manner with respect to the concentration of methionine in the culture medium. This behavior is seen in Chinese hamster ovary cells and in normal diploid and SV 40-transformed human fibroblasts. Although the kinetics of regulation of methionine adenosyltransferase and methionyl-tRNA synthetase by exogenous methionine are clearly different, the levels of the two enzymes in the human cell lines are similar.     

Effects of detergents on catalytic activity of human endometase/matrilysin 2, a putative cancer biomarker

Matrix metalloproteinases (MMPs) are a family of hydrolytic enzymes that play significant roles in development, morphogenesis, inflammation, and cancer invasion. Endometase (matrilysin 2 or MMP-26) is a putative early biomarker for human carcinomas. The effects of the ionic and nonionic detergents on catalytic activity of endometase were investigated. The hydrolytic activity of endometase was detergent concentration dependent, exhibiting a bell-shaped curve with its maximum activity near the critical micelle concentration (CMC) of nonionic detergents tested. The effect of Brij-35 on human gelatinase B (MMP-9), matrilysin (MMP-7), and membrane-type 1 MMP (MT1-MMP) was further explored. Their maximum catalysis was observed near the CMC of Brij-35 (∼ 90 μM). Their IC₅₀ values were above the CMC. The inhibition mechanism of MMP-7, MMP-9, and MT1-MMP by Brij-35 was a mixed type as determined by Dixon’s plot; however, the inhibition mechanism of endometase was noncompetitive with a K_i value of 240 μM. The catalytic activities of MMPs are influenced by detergents. Monomer of detergents may activate and stabilize MMPs to enhance catalysis, but micelle of detergents may sequester enzyme and block the substrate binding site to impede catalysis. Under physiological conditions, a lipid or membrane microenvironment may regulate enzymatic activity.     

Variation of chemical composition and antioxidant activity of essential oils of Mentha x rotundifolia (L.) Huds. (Lamiaceae) collected from different bioclimatic areas of Tunisia

The variation of the essential oils composition of 10 Tunisian Mentha x rotundifolia (L.) Huds. Populations and their antioxidant activity were assessed. Essential oils showed high percentages of oxygenated monoterpenes and sesquiterpene hydrocarbons. Rotundifolone, p-menthane-1,2,3-triol, β-caryophyllene and germacrene D were identified as main compounds at the species level. A variation in the essential oil composition was observed according to the populations and ecological factors. The populations 7, 8, 9 and 10 from the upper semi-arid bioclimatic zone and situated at high altitudes, exhibited the highest amount of rotundifolone. The populations 1, 2, 3, 4 and 5 from the lower humid showed a rotundifolone/β-caryophyllene/germacrene D chemotype. The population 6, situated at the lowest altitude, was characterized by the highest amount of p-menthane-1,2,3-triol. The level of antioxidant activity of the populations was linked to their chemical composition difference. The highest scavenging activity and the best ability to reduce ferric ions were recorded for the population 10. The most important capacity to inhibit β-carotene bleaching was revealed for the population 8. For all populations, the antioxidant activities were substantial but lower than antioxidant standards used (Trolox and BHT).The populations (7, 8, 9 and 10) from the upper semi-arid showed the best yields of essential oils and the highest contents of rotundifolone. Chemotypes within these populations could be selected for improvement programs.     

Distinct feeding strategies of generalist and specialist spiders

1. Feeding behaviour of generalist and specialist predators is determined by a variety of trophic adaptations. Specialised prey‐capture adaptations allow specialists to catch relatively large prey on a regular basis. As a result, specialists might be adapted to exploit each item of prey more thoroughly than do generalists. 2. It was expected that obligatory specialist cursorial spiders would feed less frequently than generalists but for a longer time and, thus, that their foraging pause would be longer. First, the feeding frequencies of three generalist spider species (Cybaeodamus taim, Harpactea hombergi, Hersiliola sternbergsi) were compared with those three phylogenetically related specialist species: myrmecophagous Zodarion rubidum, and araneophagous Nops aff. variabilis and Palpimanus orientalis. 3. Generalists captured more prey, exploited each item of prey for a significantly shorter time, and had a shorter foraging pause than was the case for specialists. Generalists also gained significantly less relative amount of prey mass than did specialists. 4. Second, the study compared the prey DNA degradation rate in the gut of generalists and specialists by means of PCR. The degradation rate was not significantly different between specialists and generalists: the detectability half‐life was estimated to exist for 14.3 days after feeding. 5. This study shows that the feeding strategies of cursorial generalist and obligatory specialist spiders are different. Obligatory specialists have evolved a feeding strategy that is based on thorough exploitation of a few large prey, whereas generalists have evolved a strategy that is based on short exploitation of multiple small items of prey.     

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.     

Complex patterns of grooming and sexual activity in Barbary macaques (Macaca sylvanus)

Grooming in primates is often considered a “currency” that can be exchanged for other “services” or “commodities” such as reciprocal grooming, coalitionary support, infant handling, tolerance around food sources, active food sharing, or mating opportunities. Previous studies on primate grooming‐for‐sex exchange viewed the males as the demanding class, with the females as suppliers of mating opportunities. In this study, we examine the broader context of grooming‐for‐mating exchange in Barbary macaques in Gibraltar. Our data show that Barbary macaque males groom females with whom they are mating more frequently and for longer periods than other females, and the relationship between grooming and mating remains significant in both sexual and nonsexual contexts. In addition, females groomed males with whom they were mating more frequently and for longer periods than other males. In both sexes, grooming was observed to be far more frequent and to occur for longer durations in sexual compared to nonsexual contexts. We did not find any difference in grooming behavior between presexual and postsexual contexts. Our data suggest that there is no simple model to describe Barbary macaque grooming patterns in sexual contexts. Although our results are partly consistent with male use of grooming as payment for mating, broadly assessed grooming‐mating patterns cannot be solely explained by a male‐driven grooming‐for‐mating exchange.