Long-range regulation is a major driving force in maintaining genome integrity

Background  

The availability of newly sequenced vertebrate genomes, along with more efficient and accurate alignment algorithms, have enabled the expansion of the field of comparative genomics. Large-scale genome rearrangement events modify the order of genes and non-coding conserved regions on chromosomes. While certain large genomic regions have remained intact over much of vertebrate evolution, others appear to be hotspots for genomic breakpoints. The cause of the non-uniformity of breakpoints that occurred during vertebrate evolution is poorly understood.     

Hormonal regulation of glycogen metabolism in neonatal rat liver

1. The development of active and inactive phosphorylase was determined in rat liver during the perinatal period. No inactive form could be found in tissues from animals less than 19 days gestation or older than the fifth postnatal day. 2. The regulation of phosphorylase in organ cultures of foetal rat liver was examined. None of the agents examined [glucagon, insulin or dibutyryl cyclic AMP (6-N,2'-O-dibutyryladenosine 3':5'-cyclic monophosphate)] changed the amount of phosphorylase activity. 3. Glycogen concentration in these explants were nevertheless decreased more than twofold by 4h of incubation with glucagon or dibutyryl cyclic AMP. Incubation with insulin for 4h increased the glycogen content twofold. 4. Glycogen synthetase activity was examined in these explants. I-form activity (without glucose 6-phosphate) was found to decrease by a factor of two after 4h of incubation with dibutyryl cyclic AMP, whereas I+D activity (with glucose 6-phosphate) remained nearly constant. Incubation for 4h with insulin increased I-form activity threefold, with only a slight increase in I+D activity. 5. When explants were incubated with insulin followed by addition of dibutyryl cyclic AMP, the effects of insulin on glycogen concentration and glycogen synthetase activity were reversed. 6. These results indicate that the regulation of glycogen synthesis may be the major factor in the hormonal control of glycogen metabolism in neonatal rat liver.     

Regulated adhesion as a driving force of gastrulation movements

Recent data have reinforced the fundamental role of regulated cell adhesion as a force that drives morphogenesis during gastrulation. As we discuss, cell adhesion is required for all modes of gastrulation movements in all organisms. It can even be instructive in nature, but it must be tightly and dynamically regulated. The picture that emerges from the recent findings that we review here is that different modes of gastrulation movements use the same principles of adhesion regulation, while adhesion molecules themselves coordinate the intra- and extracellular changes required for directed cell locomotion.     

Balint groups as a driving force of ego development

This paper gives an overview of one of the main components in the process of Balint groups. The paper is based on the authors' research on the work of Balint groups and the study of literature which deals with the development of ego and the role of Balint groups in the development of participants' ego. This field is of great interest to the Balint movement and education in medicine. The special place in the discussions on the Balint method is given to the issue of benefit and the nature of influence of the Balint groups on participants. The Balint movement is of special interest for Croatia since it was perhaps among the first in the world to introduce Balint seminars as an official part of education of family doctors. The Croatian Society of Balint Groups as early as in 1970's became a part of the International Federation of Balint Groups. Professor Betlheim was Michael Balint's friend and his followers introduced the method not only in medicine but also in other professions: social work, pedagogy, psychology, sociology etc. The Balint's method is also very interesting and useful to stomatologists, orthopedists and physiotherapists. Croatian dentists joined the Balint Groups in 1983 and orthopaedists in 1987. These were the unique cases in the European context. The Balint groups are very efficient and necessary in the process of strengthening ego and selfawareness of these professionals. The paper also discusses the increase of the doctor's self-awareness and self-consciousness during the process of training in the Balint Groups. The Balint Groups only insist on the doctor-patient relationship and do not interfere with the unconscious of the doctor's preoccupations. The approach of Enid Balint strives to find harmony between the Balint's approach and the psychoanalytic approach to the object of the research. According to her understanding, the development of the group atmosphere is similar to the one in the family. The authors reach a similar conclusion in their research.     

A driving force for change: interstitial flow as a morphoregulator

Dynamic stresses that are present in all living tissues drive small fluid flows, called interstitial flows, through the extracellular matrix. Interstitial flow not only helps to transport nutrients throughout the tissue, but also has important roles in tissue maintenance and pathobiology that have been, until recently, largely overlooked. Here, we present evidence for the various effects of interstitial flow on cell biology, including its roles in embryonic development, tissue morphogenesis and remodeling, inflammation and lymphedema, tumor biology and immune cell trafficking. We also discuss possible mechanisms by which interstitial flow can induce morphoregulation, including direct shear stress, matrix-cell transduction (as has been proposed in the endothelial glycocalyx) and the newly emerging concept of autologous gradient formation.     

Functional coupling as a basic mechanism of feedback regulation of cardiac energy metabolism

In this review we analyze the concepts and the experimental data on the mechanisms of the regulation of energy metabolism in muscle cells. Muscular energetics is based on the force-length relationship, which in the whole heart is expressed as a Frank-Starling law, by which the alterations of left ventricle diastolic volume change linearly both the cardiac work and oxygen consumption. The second basic characteristics of the heart is the metabolic stability--almost constant levels of high energy phosphates, ATP and phosphocreatine, which are practically independent of the workload and the rate of oxygen consumption, in contrast to the fast-twitch skeletal muscle with no metabolic stability and rapid fatigue. Analysis of the literature shows that an increase in the rate of oxygen consumption by order of magnitude, due to Frank-Starling law, is observed without any significant changes in the intracellular calcium transients. Therefore, parallel activation of contraction and mitochondrial respiration by calcium ions may play only a minor role in regulation of respiration in the cells. The effective regulation of the respiration under the effect of Frank-Starling law and metabolic stability of the heart are explained by the mechanisms of functional coupling within supramolecular complexes in mitochondria, and at the subcellular level within the intracellular energetic units. Such a complex structural and functional organisation of heart energy metabolism can be described quantitatively by mathematical models.     

Prey availability in time and space is a driving force in life history evolution of predatory insects

Environmental constraints can be determinant key factors conditioning predator life history evolution. Prey seems to have conditioned life history evolution in their ladybird predator, with the predators of aphids apparently presenting faster development, greater fecundity and shorter longevity than species preying on coccids. However a rigorous comparison has never been done. We hypothesize that aphids and coccids differ by their developmental rate, abundance, and distribution in the field, which act as ecological constraints promoting life history evolution in ladybird predators. Field data reveal that aphids are ephemeral resources available in the form of large colonies randomly distributed in the habitat whereas coccids form smaller colonies that tend to be aggregated in space and available for longer periods. A comparison in laboratory conditions of two predatory species belonging to the tribe Scymnini (Coleoptera: Coccinellidae) show that the aphidophagous species lives at a faster pace than the coccidophagous: it develops faster, matures earlier, is more fecund, has a shorter reproductive life-span and allocate proportionally more fat in its gonads relative to soma. This indicates that the life histories of aphidophagous and coccidophagous ladybird predators appear to have evolved in response to particular patterns of prey availability in time and space. Under the light of these results, the existence of a slow-fast continuum in ladybirds is briefly addressed.     

Predation risk as a driving force for phenotypic assortment: a cross-population comparison

Frequency-dependent predation has been proposed as a general mechanism driving the phenotypic assortment of social groups via the ‘oddity effect’, which occurs when the presence of odd individuals in a group allows a predator to fixate on a single prey item, increasing the predator''s attack-to-kill ratio. However, the generality of the oddity effect has been debated and, previously, there has not been an ecological assessment of the role of predation risk in driving the phenotypic assortment of social groups. Here, we compare the levels of body length assortment of social groups between populations of the Trinidadian guppy (Poecilia reticulata) that experience differences in predation risk. As predicted by the oddity effect hypothesis, we observe phenotypic assortment by body length to be greater under high predation risk. However, we found that a number of low-predation populations were also significantly assorted by body length, suggesting that other mechanisms may have a role to play.     

Hormonal regulation of benzo[a]pyrene metabolism in human adrenocortical cell cultures

In cultured fetal human adrenocortical cells, metabolism of the carcinogen benzo[a]pyrene was found to be unresponsive to the xenobiotic inducers 3-methylcholanthrene, benz[a]anthracene and 2,3,7,8-tetrachlorodibenzo-p-dioxin. However, exposure of cultures to the hormone adrenocorticotropin (ACTH) for 48 hours stimulated benzo[a]pyrene metabolism 3-fold. The major metabolite was the 7,8-diol. Other compounds which stimulate the production of adrenocortical cell cyclic AMP (forskolin and cholera toxin) as well as monobutyryl cyclic AMP also increased benzo[a]pyrene metabolism. Human adrenocortical cells thus provide an unusual example of hormonal regulation of the metabolism of a carcinogen.