Search results for "Mechanism"
showing 10 items of 1835 documents
Predatory behavior in the genusLeptogenys: A comparative study
1997
We studied the predatory behavior of seven species of the genusLeptogenys from Mexico and Cameroon. The ants of this genus are armed with long, thin, curved mandibles articulated at the extreme corners of the anterior margin of the head, permitting them easily to seize oniscoid isopods, the obligate or the principal prey of mostLeptogenys species. Workers hunt these prey, which are able to roll themselves up, solitarily. Foraging behavior comprises sequences of up to eight activities. The prey can be seized by the body (rolled up or not), or alternatively by the edge of the shell, then turned over and stung on the ventral face. A relationship between the mandible size of the workers and the…
Food availability and the male's role in parental care in double-brooded TreecreepersCerthia familiaris
1996
The aim of this work was to examine differences in paternal and maternal care in a double-brooded, monogamous species, the Treecreeper Certhia familiaris, in relation to food availability. As a measure of parental care, we recorded the hourly feeding activity of parents when the nestlings from their first and second breeding attempts were 7 and 12 days old. Feeding frequency of the first brood increased with the age of the nestlings and also with the brood size when 12 days old. While the feeding activities of the females were similar with respect to the first and second broods, the males were less active and failed to provide any food to their nestlings in 15 cases out of 28 second broods.…
How a Second Mg2+ Ion Affects the Phosphoryl Transfer Mechanism in a Protein Kinase: A Computational Study
2020
<div>In this contribution, the phosphoryl transfer reaction in CDK2 has been studied in detail considering the presence of an additional Mg2+ ion in the active site. For this purpose, QM/MM (quantum mechanics/molecular mechanics) free energy calculations with the adaptive string method were performed, which showed that indeed the system containing two Mg2+ ions exhibits a lower activation free energy, corroborating the experimental observations.</div>
Female Attraction Behaviour of Radio Tagged Polyterritorial Pied Flycatcher Males
1993
AbstractPolygynous mating is costly for pied flycatcher (Ficedula hypoleuca) females. Thus, females have a good reason to attempt to avoid mating with already mated polyterritorial males. One cue to disclose a male's mating status is his behaviour. The behaviour of polyterritorial and unmated males was studied by radio tagging that allows accurate recording of male movements. While attracting a secondary female polyterritorial males spent significantly less time on the secondary territory than did unmated males on their single territory. Polyterritorial males also tended to have lower song rates. When a female appeared on the secondary territory of polyterritorial males, they increased the …
ChemInform Abstract: Design, Synthesis, DNA-Binding and Cytotoxicity Evaluation of New Potential Combilexines.
2010
Combilexines, compounds in which a DNA intercalator is linked to a minor groove binding component, interact with the DNA in a sequence specific manner to yield in most cases compounds with anticancer activity. A series of new compounds closely related to netropsin in which the two components were linked by an amide group was synthesised as potential combilexines. As some of these compounds showed cytotoxic activity in vitro, an attempt was made to rationalise their mechanism of action. The DNA binding characteristics of the carboxamides were evaluated by thermal denaturation experiments and by ethidium bromide displacement assay. Their ability to inhibit the topoisomerase I was also determi…
Agonistic and sociable behaviors in the mound-building mice,Mus spicilegus: A comparative study withMus musculus domesticus
2001
Present social organization and mating systems result from selective pressures and ecological conditions but also from proximate interactions between individuals. Many studies report on a polygynous mating system with a social group territoriality in commensal populations of Mus musculus domesticus. However, little is known about the social organization of other Mus species living in outdoor conditions, such as the mound-building mouse Mus spicilegus. Comparative studies between M. m. domesticus and M. spicilegus have already shown behavioral differences in female sexual preferences and paternal care. To study agonistic and sociable interactions and gain insight into the social organization…
OZONE THERAPY: MECHANISMS OF ACTION, RECENT LITERATURE AND NEWLY DISCOVERED BIOCHEMICAL PATHWAYS
2018
Ozone therapy is widely used in many countries since many years. Recently, the increasing widespread of this complementary therapy has been accomplished by an increased number of basic and clinic papers published on international journals. This lecture will deal on the first approach by a pharmacological point of view in the aim to characterize the mechanisms activated at sub-cellular level by ozone when used for medical and beauty application at low graded doses. The first theory was based upon the fact that the exposure to low, non-toxic, ozone concentrations could increase the efficacy of the endogenous antioxidant system by increasing the production or the activity of some enzymes exert…
Correlation between osteoporosis and cardiovascular disease
2014
Several evidences have shown in the last years a possible correlation between cardiovascular diseases and osteoporosis. Patients affected with osteoporosis, for example, have a higher risk of cardiovascular diseases than subjects with normal bone mass. However, the heterogeneous approaches and the different populations that have been studied so far have limited the strength of the findings. Studies conducted in animal models show that vascular calcification is a very complex mechanism that involves similar pathways described in the normal bone calcification. Proteins like BMP, osteopontin, osteoprotegerin play an important role at the bone level but are also highly expressed in the calcifie…
Natural Triterpenoids as Anti-Inflammatory Agents
2000
Abstract This chapter reviews the natural triterpenes with anti-inflammatory activity, including the traditional ones and the new compounds isolated over the last six years. Triterpenes are widely distributed in plants, and in many cases are the principles responsible for their anti-inflammatory effects. Many of these compounds are active in different in vivo experimental models such as hind paw edema induced by carrageenan, serotonin and phospholipase A2; ear edema induced by phorbol and daphnane esters, ethylphenylpropiolate, arachidonic acid and capsaicin; adjuvant arthritis and experimental models of allergy. Other effects have been studied in vitro, and some triterpenes are active agai…
Cowbird versus cuckoo hosts: a comparative study of learned nest defense
2005
One of the best example of coevolutionaru adaptations is that of the interactions between avian brood parasites and their hosts. Brood parasites lay their eggs in nests of other specieis and leave the job of caring for their young with the hosts. Hosts of brood parasites tend to suffer high reproductive costs as often they raise few of no young of their own, an effect of being parasitizes. For this reason, many hosts have evolved strategies that reduces the cost of parasitism.