The BAR-domain family of proteins: a case of bending and binding?

BAR-domains recently took centre stage in science through a report on the crystal structure of this domain in Drosophila Amphiphysin. Though only weakly conserved at the sequence level, the structure of the BAR domain shows striking similarity to the GTPase-binding domain of Arfaptin 2, an effector of Rho- and Arf- GTPases. On the basis of this sequence and structural similarity, these two proteins have been classified as belonging to the same family, the BAR-domain family, and they probably also have similar functional characteristics. Presented here are the results of a database search for the sequence of the BAR domain of Amphiphysin and Arfaptin 2. This search identified a variety of related proteins, most of which are involved in intracellular transport and especially in endocytosis. For example, the BAR-domain family includes Endophilins, GTPase-activating proteins of the Centaurinbeta family and Oligophrenins, the adaptor proteins APPL1 and APPL2 that were recently shown to interact with the small GTPase Rab5, as well as members of the Sorting nexin family. On the basis of the structures of Amphiphysin and Arfaptin 2 and the cellular role of Amphiphysins in the early steps of endocytosis, the functions of the BAR domain have been defined as a dimerization motif and as sensing and inducing membrane curvature. However, data on Arfaptin 2 and now also on the Adaptor proteins APPL1 and 2 suggest that another function of the BAR domain is to bind to small GTPases.     

Do frogs use retinal elevation to measure the distance of a barrier?

Grass frogs, Rana pipiens, will detour around a barrier to reach prey on the other side. However, if the distance between prey and barrier is short, frogs attempt to push through the barrier and reach the prey directly. The relationship between the probability of detouring and the distance between prey and barrier is the same whether the frog's starting position is 4 cm or 8 cm from the barrier. This suggests that frogs measure the absolute separation between the two objects. To discover whether the retinal elevation of the bottom of the barrier contributes to measuring this distance, the relationship between the frequency of detouring and barrier-prey distance was examined in several experiments in which the retinal position of the bottom of the barrier was manipulated. No evidence was obtained that the barrier's retinal elevation helps in gauging distance.On the other hand, retinal elevation influences strongly how far a frog lunges to reach its prey. It is suggested that different cues to distance are applied to the two classes of object because, under natural circumstances, it is difficult to judge where a barrier emerges from the ground. A barrier may be hard to detect below the horizon because of the low contrast between it and the ground, or because vegetation and ground litter mask where the barrier meets the ground. In contrast, the prey's movements make it easily detectable against a stationary background and the prey's short height means that partial occlusion will have little effect on its apparent vertical position in the visual field.     

The Great Wall of China: a physical barrier to gene flow?

One population from each of six plant species along both sides of the Juyong-guan Great Wall, together with one population from each of five species along both sides of a path on a mountain top near Juyong-guan, were selected to study the effect of the Great Wall as a barrier on genetic differentiation between two subpopulations using RAPD markers. Significant genetic differentiation was found between the subpopulations on both sides of the Great Wall. A wind-pollinated woody species, Ulmus pumila, showed less genetic differentiation than four insect-pollinated species: Prunus armeniaca, Ziziphus jujuba, Vitex negundo, and Heteropappus hispidus. Cleistogenes caespitosa, a wind-pollinated perennial herb, displayed more genetic differentiation between subpopulations than the insect-pollinated species because of its propagation strategy. Although AMOVA analysis showed that subpopulations divided by a mountain path had diverged genetically, the variance component between the subpopulations on both sides of the Great Wall was significantly larger than that between the subpopulations at the control site. Therefore, it is reasonable to deduce that the Juyong-guan Great Wall has served as a physical barrier to gene flow between subpopulations separated for more than 600 years.     

The surf zone: a semi-permeable barrier to onshore recruitment of invertebrate larvae?

The supply of larvae to the shore is important for population replenishment and intertidal community dynamics but its variability at most scales is not well understood. We tested the relationship between nearshore mussel larval abundance and intertidal settlement rates over several years at multiple spatiotemporal scales in Oregon and New Zealand. Abundance of competent larvae nearshore and intertidal recruitment rates were simultaneously quantified using collectors mounted at different depths on moorings 50-1100 m from shore, and at adjacent rocky intertidal sites. Total mussel larval abundance and oceanographic conditions were also measured in some locations. At all scales, abundance of nearshore mussel larvae was unrelated to intertidal recruitment rates. In the intertidal, patterns of mussel recruitment were persistent in space, with sites of consistently high or low recruitment. In contrast, nearshore competent larval abundance showed generally similar abundances among sites except for a high, and spatially-inconsistent, variability in Oregon during 1998 only. On moorings, recruitment tended to be greater on midwater collectors than shallower or deeper. Finally, on moorings larval abundance in traps and recruitment on collectors was unrelated. These results suggest that (1) among sites, the size of the nearshore larval pool is relatively uniform while onshore recruitment varies and is unrelated to larval abundance, (2) temporal variability in nearshore larval availability is not strongly expressed onshore, (3) vertical stratification of competent larvae nearshore is strong and may influence transport and recruitment, and (4) within-coast variability in onshore recruitment is strongly driven by processes occurring locally within the surf zone that need to be studied to understand coastal recruitment dynamics.     

Colposcopy in a family planning clinic: a future model?

The first year''s experience of a satellite colposcopy clinic in the Glasgow Family Planning Centre was analysed. Establishment of the clinic was supervised by an experienced member of the colposcopy team at the department of gynaecology, Western Infirmary, Glasgow, who trained one of the family planning centre''s staff. Close links were thus maintained with the hospital clinic to which patients were referred for treatment. The policy at the new colposcopy clinic was to study prospectively all women in the hospital catchment area whose cervical smears were reported as abnormal. In 58 of 162 such patients there was at least moderate dyskaryosis and the cytologist''s recommendation had been referral for colposcopy. In 104 cases the changes were either atypia alone or mild dyskaryosis and a repeat smear was recommended within three to 12 months; 18 of these patients had grade II or III cervical intraepithelial neoplasia on biopsy, and relying on repeat smears would have resulted in an 11.7% false negative rate. If an atypical cytological picture is to be an indication for colposcopy clinics attached to family planning centres may have an important role, given satisfactory training and close links with central specialist colposcopy clinics.     

Are indirect measures of abundance a useful index of population density? The case of red grouse harvesting

Indirect measures of population abundance, such as harvest data, are often used to make inference on long term population dynamics when direct data are either not available or are logistically difficult to obtain. However, when harvesting records are used, a common concern is that they may not reflect actual population abundance. We investigated the extent to which harvest data reflected changes in population density of the red grouse Lagopus lagopus scoticus in Great Britain. We used 92 independently managed populations over the period 1977–2000 and examined the temporal and spatial variability of the hunting records and independently obtained count data from each of these managed estates. Three different analyses support the conclusion that grouse hunting records are a reliable indicator of grouse abundance: 1) the number of red grouse shot in autumn showed a tendency to be linearly related to the density of individuals counted in the summer prior to the harvesting, 2) the relationships between the variance and the mean in the harvesting and corresponding count data, calculated over different populations at the same time, or the same locations at different times, were not statistically distinguishable, 3) similar direct and delayed density dependence patterns were observed in hunting records and count data. Our results suggest that red grouse hunting time series are a good proxy for population abundance.     

What's in a name? The case of cyanobacteria

A redefinition of the cyanobacterial lineage has been proposed based on phylogenomic analysis of distantly related nonphototrophic lineages. We define Cyanobacteria here as “Organisms in the domain bacteria able to carry out oxygenic photosynthesis with water as an electron donor and to reduce carbon dioxide as a source of carbon, or those secondarily evolved from such organisms.”     

The use of a rare codon specifically during development?

A range of circumstantial evidence suggests that in Streptomyces spp., genes required for vegetative growth do not contain the leucine codon TTA. Instead, the codon seems to be confined to a few genes necessary during differentiation, when the colonies begin to produce aerial hyphae and antibiotics. Thus, mutations in bldA, the structural gene for tRNATTALeu, do not retard vegetative growth, but they prevent normal aerial mycelium and antibiotic production. Most of the known TTA-containing genes specify regulatory or resistance proteins associated with antibiotic-production clusters. Possibly the ability to translate the UUA codons in mRNA from such genes is confined to late stages of colony development. Factors that might have contributed to the evolution of this unusual situation are discussed.     

The CCN family: a new class of inflammation modulators?

Uncontrolled or sustained inflammation is the underlying cause of or actively contributes to the progression of many chronic pathologies such as atherosclerosis, arthritis, or neuroinflammatory diseases. Matricellular proteins of the CCN family (CYR61/CTGF/NOV) have emerged as localized multitasking signal integrators. These structurally conserved secreted proteins specifically interact with and signal through various extracellular partners, in particular integrins, which enable them to play crucial roles in various processes including development, angiogenesis, wound healing and diseases such as fibrosis, vascular disease and cancer. In this review, we discuss the possibility that the CCN family members could represent a putative new class of modulators of inflammation. In this context, we focused on their relationship with cytokines and chemokines. In vitro, CCN expression is finely regulated by diverse inflammatory mediators including cytokines (TNFα, IL1β, TGF-β), small factors such as prostaglandins, nitric oxide, histamine and serotonin, and extracellular matrix enzymes. In addition, CCN proteins acting alone or in concert with their specific partners appear to be potent regulators of the production of cytokines and chemokines in a context-dependent manner. Finally, emerging studies suggest a potential role for CCN proteins in chronic inflammatory diseases such as atherosclerosis, rheumatoid arthritis, inflammatory kidney diseases and neuroinflammatory pathologies such as Alzheimer’s disease. CCN members could therefore represent new potential therapeutic targets for drug development against such diseases.     

What is a category? The case of rough-and-tumble play

The intent of this paper is to outline a process by which we redefined an ambiguous behavioral category, rough-and-tumble play (R&T), using ethological and ethnographic methods (i.e., factor analyses, motivational/functional analyses, and interviews). Results suggest that sociometrically rejected and popular elementary school children have different concepts of R&T. For the former group, R&T and aggression seem to be interrelated and serve similar functions, while for the latter group R&T is a playful, social affiliative category. Interview results suggest that a cognitive processing difference between the groups may be at the root of this difference.     

Are we failing our teenagers? Value of a family planning service for teenagers within the sexually transmitted disease clinic.

Out of 100 teenage girls attending a sexually transmitted disease clinic for the first time, 77 were found to be using a reliable method of contraception and had similar characteristics to teenage girls attending a family planning clinic. The 23 girls not using any reliable contraception exhibited a different pattern of sexual behaviour and were at high risk of unplanned pregnancy. Subsequently, another group of 23 girls not using contraception when seen at the sexually transmitted disease clinic were actively encouraged to attend a family planning clinic. Their risk of unplanned pregnancy was much reduced, although their pattern of sexual activity was unchanged. Ready availability of contraceptive advice for unprotected teenagers in sexually transmitted disease clinics would reduce their high risk of unplanned pregnancy.     

The astrocyte/meningeal cell interface – a barrier to successful nerve regeneration?

Following injuries to the adult mammalian CNS meningeal cells migrate into the lesion cavity, forming a fibrotic scar and accessory glia limitans. This infiltration re-establishes the meningeal layer that normally surrounds the CNS, and so reforms the barrier between the CNS and external environment, thus protecting the damaged region from events outside it. However, the newly formed meningeal layer and glia limitans may impede subsequent nerve regeneration through the injured region. This structure can be modelled in vitro using an astrocyte/meningeal co-culture system. We have examined patterns of neurite outgrowth on such cultures, and we find that axons cross readily from meningeal cells to astrocytes, but are unwilling to cross in the other direction. The distribution of cell surface and matrix molecules on these cultures is described, and the effect of various pharmacological interventions which can affect axon growth between the two cell types is summarised in this review.     

Are the pH-sensitive mutants members of theVMA family?

This work was supported by Grant 7S 203 013 07.     

How ecosystems adapt to face disruptive impact? The case of a commercial harbor benthic community

Commercial harbors are commonly considered as definitively lost environment sacrificed in the name of economic development, but, recently, a growing attention has been addressed to harbor ecology and harbor ecological state. The objective of this research is to identify the adaptation strategy carried out by the benthic community of Voltri harbor (NW Italy) by means of the application of a set of whole system metrics. Thermodynamic and network analysis revealed harbor benthic community characterized by an efficient and active network but also scarcely able to maintain complex structures and organisms. These results can be interpreted as evidences of adaptations carried out by the harbor benthic community that revealed itself healthy even if poorly resilient and thus not able to face further disturbances.