What is the proximate cause for size‐dependent ecophysiological differences in vascular epiphytes?

Size-related variation in physiological parameters as diverse as photosynthetic capacity, abscisic acid relationships or the relative water deficit at stomatal closure have been reported for a large number of vascular epiphytes, but the proximate mechanism behind these observations has not been identified. We test four possible reasons for size-related changes in photosynthetic capacity, leaf-N content and specific leaf area: (i) plant size itself, (ii) plant age or developmental stage, (iii) previous nutrition, or (iv) previous water regime. A suite of study species and approaches were used: a 'natural experiment' with the orchid Polystachya foliosa; an experimental field study with another orchid, Dimerandra emarginata; and a study under controlled conditions with the tank bromeliad, Vriesea sanguinolenta. Neither size, age nor differences in water supply caused differences in leaf N and photosynthetic capacity, while low supply of nutrients yielded, and high supply with nutrients completely removed, size-related trends. The observed size-related trends are thus a consequence of in situ differences in nutrient acquisition. Arguably, the improved nutrient status of larger plants under natural conditions results from larger tanks, holding moisture for increasingly longer intervals, which allows longer periods of decomposition of detritus and of nutrient uptake.     

What is the required minimum landscape size for dispersal studies?

Among small animals dispersal parameters are mainly obtained by traditional methods using population studies of marked individuals. Dispersal studies may underestimate the rate and distance of dispersal, and be biased because of aggregated habitat patches and a small study area. The probability of observing long distance dispersal events decreases with distance travelled by the organisms. In this study a new approach is presented to solve this methodological problem. An extensive mark-release-recapture programme was performed in an area of 81 km(2) in southern Sweden. To estimate the required size of the study area for adequate dispersal measures we examined the effect of study area size on dispersal distance using empirical data and a repeated subsampling procedure. In 2003 and 2004, two species of diurnal burnet moths (Zygaenidae) were studied to explore dispersal patterns. The longest confirmed dispersal distance was 5600 m and in total 100 dispersal events were found between habitat patches for the two species. The estimated dispersal distance was strongly affected by the size of the study area and the number of marked individuals. For areas less than 10 km(2) most of the dispersal events were undetected. Realistic estimates of dispersal distance require a study area of at least 50 km(2). To obtain adequate measures of dispersal, the marked population should be large, preferably over 500 recaptured individuals. This result was evident for the mean moved distance, mean dispersal distance and maximum dispersal distance. In general, traditional dispersal studies are performed in small study areas and based on few individuals and should therefore be interpreted with care. Adequate dispersal measures for insects obtained by radio-tracking and genetic estimates (gene flow) is still a challenge for the future.     

How common is the funnel‐like energy landscape in protein‐protein interactions?

The goal of this study is to verify the concept of the funnel-like intermolecular energy landscape in protein-protein interactions by use of a series of computational experiments. Our preliminary analysis revealed the existence of the funnel in many protein-protein interactions. However, because of the uncertainties in the modeling of these interactions and the ambiguity of the analysis procedures, the detection of the funnels requires detailed quantitative approaches to the energy landscape analysis. A number of such approaches are presented in this study. We show that the funnel detection problem is equivalent to a problem of distinguishing between distributions of low-energy intermolecular matches in the funnel and in the low-frequency landscape fluctuations. If the fluctuations are random, the decision about whether the minimum is the funnel is equivalent to determining whether this minimum is significantly different from a would-be random one. A database of 475 nonredundant cocrystallized protein-protein complexes was used to re-dock the proteins by use of smoothed potentials. To detect the funnel, we developed a set of sophisticated models of random matches. The funnel was considered detected if the binding area was more populated by the low-energy docking predictions than by the matches generated in the random models. The number of funnels detected by use of different random models varied significantly. However, the results confirmed that the funnel may be the general feature in protein-protein association.     

Geriatric dentistry: is rethinking still required? A community‐based survey in Indian population

Gerodontology 2012; doi: 10.1111/j.1741‐2358.2012.00667.x Geriatric dentistry: is rethinking still required? A community‐based survey in Indian population Background: India has a large geriatric population (60 years and above) of 77 million; comprising 7.7% of its total population. Poor oral health and loss of teeth not only adversely affect the dietary intake and nutritional status and thereby compromise general health, but can also deny them the pleasure of eating food of their choice. Objective: To assess the level of edentulousness, denture wearing and denture needs of the elderly in the community and to study the correlation between oral health parameters and sociodemographic variables which would help us to define better treatment modalities, counselling and thus improve the oral health of our geriatric patients. Materials and Methods: Subjects who were 60 years and above were considered for this study and were randomly selected. Of the 1360 elderly who were enrolled in the study, 780 (57.35%) were males and 580 (42.64%) were female. This sample size is in proportion to the total population for the pilot study. They were given an oral examination and a questionnaire. Results: Fifty seven percent (57%) of the elderly were not satisfied with their oral health status and function. Conclusion: Complete edentulousness of both the arches was highest in the middle socio‐economic group, and was the lowest in the low socio‐economic group. Less than 50% of edentulous elderly and only 10% of partially edentulous elderly were wearing dentures.     

α-Syntrophin is required for the hepatocyte growth factor-induced migration of cultured myoblasts

Syntrophins are adaptor proteins that link intracellular signaling molecules to the dystrophin based scaffold. In this study, we investigated the function of syntrophins in cell migration, one of the early steps in myogenic differentiation and in regeneration of adult muscle. Hepatocyte growth factor (HGF) stimulates migration and lamellipodia formation in cultured C2 myoblasts. In the migrating cells, syntrophin concentrated in the rear-lateral region of the cell, opposite of the lamellipodia, instead of being diffusely present throughout the cytoplasm of non-migrating cells. When the expression of α-syntrophin, the major syntrophin isoform of skeletal muscle, was reduced by transfection with the α-syntrophin-specific siRNA, HGF stimulation of lamellipodia formation was prevented. Likewise, migration of myoblasts from α-syntrophin knockout mice could not be stimulated by HGF. However, HGF-induced migration was restored in myoblasts isolated from a transgenic mouse expressing α-syntrophin only in muscle cells. Treatment of C2 myoblasts with inhibitors of PI3-kinase not only reduced the rate of cell migration, but also impaired the accumulation of syntrophins in the rear-lateral region of the migrating cells. Phosphorylation of Akt was reduced in the α-syntrophin siRNA-treated C2 cells. These results suggest that α-syntrophin is required for HGF-induced migration of myoblasts and for proper PI3-kinase/Akt signaling.     

Is fungal species richness and composition related to the occurrence of the old‐growth associated wood‐decaying Amylocystis lapponica?

Amylocystis lapponica (Romell) Singer is a widely distributed wood‐decaying polypore fungus found throughout the Northern Hemisphere. Despite its huge distribution range it occurs rather patchily and seems narrowly associated with old‐growth forest stands. Notably, it has been used as an ‘indicator species’, believed to reflect the long‐term presence of dead wood, naturalness of forest stands, and indirectly, species richness and possibly composition. In this study we focused on the last issue – whether or not there is a link between the occurrence of A. lapponica and the species richness and composition of other wood‐decaying fungi. Selecting log characteristics and microclimate as similar as possible, we compared 12 logs with and 12 logs without visible fruit bodies of A. lapponica to examine: 1) if visible fruit bodies corresponded with molecular identification of the mycelia, 2) if fungal species richness and composition of the substrate were related to A. lapponica occurrence, and 3) if A. lapponica was restricted to certain parts of the log. Fungal species were recorded by inspecting visible fruit bodies and by culture isolation and ITS sequencing from wood disc samples. Laboratory and field identification of A. lapponica had 71% correspondence, and mycelia were identified in two logs without visible fruit bodies. Twice as many fungal species were detected using ITS sequencing compared to fruit body identification. Total species richness was similar between the two log categories, but number of species per log was slightly higher in A. lapponica logs. Antrodia serialis (Fr.) Donk, and possibly also Fomitopsis pinicola (Sw.:Fr.) P. Karst. and Phellinus nigrolimitatus (Romell) Bourdot & Galzin, occurred more frequently in A. lapponica logs. Mycelia of A. lapponica were restricted to less decayed parts of the wood in the centre of the middle part of the logs.     

Boom to bust? Implications for the continued rapid growth of the eastern Australian humpback whale population despite recovery

Despite heavy overexploitation and near extirpation, some populations of large whales are recovering. Monitoring their recovery has important implications for conservation, management and our understanding of population dynamics and recovery in large mammals. The eastern Australian population of humpback whales was hunted to near-extirpation by the early 1960s. Despite this, the population started to recover, and structured surveys were initiated in the 1980s. These surveys comprise one of the longest and most consistent series of surveys of a population of whales in the world. Collectively, they have demonstrated a rapid recovery of the population with a long-term average rate of increase of 10.9% per annum. Here, we present the results of the last three surveys, conducted in 2007, 2010 and 2015. The 2015 survey shows that the population is essentially recovered, with abundance estimated at 24,545 whales (95% confidence interval 21,631–27,851), and yet continues to grow at a rapid rate. Modeling the rate of growth and abundance suggests that either the whales are heading for a higher than expected abundance of at least 40,000 whales or that an irruption may occur with models suggesting a peak in whale abundance in 2021–2026. Understanding the possible future scenarios of this population is critical to its management. This situation also presents a rare opportunity to study in detail the growth of a well-defined population of large mammal as it recovers from severe depletion.     

When can the cause of a population decline be determined?

Inferring the factors responsible for declines in abundance is a prerequisite to preventing the extinction of wild populations. Many of the policies and programmes intended to prevent extinctions operate on the assumption that the factors driving the decline of a population can be determined. Exogenous factors that cause declines in abundance can be statistically confounded with endogenous factors such as density dependence. To demonstrate the potential for confounding, we used an experiment where replicated populations were driven to extinction by gradually manipulating habitat quality. In many of the replicated populations, habitat quality and density dependence were confounded, which obscured causal inference. Our results show that confounding is likely to occur when the exogenous factors that are driving the decline change gradually over time. Our study has direct implications for wild populations, because many factors that could drive a population to extinction change gradually through time.     

When is Open‐endedness Desirable in Restoration Projects?

A low‐intervention approach to restoration that also allows restoration outcomes to be framed as trajectories of ecosystem change can be described as “open‐ended” restoration. It is an approach which recognizes that long‐term ecosystem behavior involves continual change at small and large spatial and temporal scales. There are a number of situations in which it is appropriate to adopt an open‐ended approach to restoration including: in remote and large areas, where ecological limiting factors will be changed by future climates, where antecedent conditions cannot be replicated, where there are novel starting points for restoration, where restoration relies strongly on processes outside the restoration area, in inherently dynamic systems, where costs are high and where the public demands “wildness.” Where this approach is adopted managers need to explain the project and deal with public expectations and public risk. Monitoring biotic and abiotic components of the project are very important as an open‐ended approach does not equate to “abandon and ignore it.”     

Why are leaf‐cutting ants more common in early secondary forests than in old‐growth tropical forests? An evaluation of the palatable forage hypothesis

I evaluated the hypothesis that leaf‐cutting ants are more common in early successional forests than in old‐growth forests because pioneer species, which dominate in early successional habitats, appear more susceptible to leafcutters than shade‐tolerant species, which dominate primary forests (palatable forage hypothesis). The relative importance of pioneer and shade‐tolerant species as plant resources for leaf‐cutting ant colonies was evaluated (1) by literature review of leaf‐cutting ants’ diet, and (2) experimentally, using field assays to determine leafcutter's selectivity. Pioneer species were harvested three times more frequently than shade‐tolerant species and made up the largest component of the diet in all the studies reviewed. The amount harvested was not correlated with the plant species abundance. In addition, leaves from pioneer plants were selected eight times more than leaves from shade‐tolerant species in the field assays. These results support the palatable forage hypothesis. Leafcutters probably select pioneer leaves because of their low level of chemical defenses and high nutrient content. The high availability of pioneer species in early successional forest probably decreases the cost to locate palatable resources. Therefore, early successional habitats support more ant colonies than old‐growth forests. On the other hand, the effective defense mechanisms of mature plant species and the high dispersion of palatable plants could explain the low density of leaf‐cutting ant colonies in old‐growth forests. The palatable forage hypothesis is compared with other hypotheses that explain leaf‐cutting ant density. The preference of foundress queens for forest clearings, the dependence of small colonies on herbs, and the importance of pioneer plant species for mature colonies (palatable forage hypothesis) can be considered complementary, because they focus on different stages of the colony's life history. Consequently, the availability of pioneer plants appears to be one of the most influential factors determining mature leaf‐cutting ant nest densities in Neotropical forests.     

Seasonal variation in the population growth rate of a dominant zooplankter: what determines its population dynamics?

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What limits clutch size? A test of the incubation‐capacity hypothesis in a high‐elevation population of Mountain Bluebirds

Most studies of factors that limit the number of eggs that birds lay have focused on the disadvantages of having too many young to feed. Less attention has been paid to the consequences of having a large number of eggs to incubate. The incubation‐capacity hypothesis proposes that females lay as many eggs as they can effectively incubate. We tested this hypothesis in 2018 in a montane population of Mountain Bluebirds (Sialia currucoides). Most females in this population lay five or six eggs; clutches of seven occur, but are rare. We added eggs to some nests, forcing females to incubate seven eggs, while leaving other nests as controls. Among females completing incubation, those with enlarged clutches hatched as many eggs as did control females, and did so in the same amount of time. This was despite an extended period of unusually cold and often wet weather that occurred when many females were incubating. Our results firmly reject the suggestion that females typically lay no more than six eggs because they cannot effectively heat seven eggs. One or more other factors must limit clutch size. One possible factor is suggested by the fact that during the period of inclement weather, more females with enlarged clutches than control females appeared to abandon nests before completing incubation. Because larger clutches require more energy to incubate, females with seven eggs during energetically stressful conditions could more quickly reach the point where they lack sufficient energy for both incubation and self‐maintenance. Such conditions may occur frequently enough in the montane environment that, on average, laying seven eggs results in reduced lifetime reproductive success.     

Maturational profiles and migration in the female adolescent population of Madrid: is there a need for a new perspective?

The aim of this study is to assess anthropometric changes and menstrual cycle characteristics during the maturation process of an adolescent female sample in Madrid, Spain. The new demographic context of Madrid, with a 33.9% of girls coming from Central and South America, makes this study relevant in terms of new epidemiological situations that could possible develop. The sample consists of 284 girls, ages 9 to 16 years, measured and interviewed in four school centres of Madrid. Results show that menarche is slightly earlier in the Spanish girls, but there are no other important differences regarding the characteristics of their menses. However, the Spanish girls have a significantly higher intake of menarcheal pain related drugs. The anthropometric changes accompanying menarche are greater in the immigrants, especially in terms of trunk fatness, leading to an "overweight" characterisation of this sub-sample. These maturational profiles show the need for educational programs, especially focussed on the foreign adolescent population, to cope with health risks related to overweight.     

What is the minimum number of letters required to fold a protein?

Experimental studies have shown that the full sequence complexity of naturally occurring proteins is not required to generate rapidly folding and functional proteins, i.e. proteins can be designed with fewer than 20 letters. This raises the question of what is the minimum number of amino acid types required to encode complex protein folds? Here, we investigate this issue from three aspects. First, we study the minimum sequence complexity that can reserve the necessary structural information for detection of distantly related homologues. Second, we compare the ability of designing foldable model sequences over a wide range of reduced amino acid alphabets, which find the minimum number of letters that have the similar design ability as 20. Finally, we survey the lower bound of alphabet size of globular proteins in a non-redundant protein database. These different approaches give a remarkably consistent view, that the minimum number of letters required to fold a protein is around ten.