How well is current plant trait composition predicted by modern and historical forest spatial configuration?

There is increasing evidence to suggest that a delayed response of many forest species to habitat loss and fragmentation leads to the development of extinction debts and immigration credits in affected forest habitat. These time lags result in plant communities which are not well predicted by present day landscape structure, reducing the accuracy of biodiversity assessments and predictions for future change. Here, species richness data and mean values for five life history characteristics within deciduous broadleaved forest habitat across Great Britain were used to quantify the degree to which aspects of present day forest plant composition are best explained by modern or historical forest patch area. Ancient forest specialist richness, mean rarity and mean seed terminal velocity were not well predicted by modern patch area, implying the existence of a degree of lag in British forest patches. Mean seedbank persistence values were more closely related to modern patch area than historical, particularly in larger patches. The variation in response for different mean trait values suggests that species respond to landscape change at different rates depending upon their combinations of different trait states. Current forest understorey communities are therefore likely to consist of a mixture of declining species whose extinction debt is still to be paid, and faster colonising immigrant species. These results indicate that without management action, rare and threatened species of plant are likely to be lost in the future as a result of changes in forest spatial configuration that have already taken place. The lag seen here for rare specialist plants suggests however that there may still be scope to protect such species before they are lost from forest patches.     

The complexity of forest borders determines the understorey vegetation

Questions

What are the most important drivers of plant species richness (gamma‐diversity) and species turnover (beta‐diversity) in the field layer of a forest edge? Does the tree and shrub species richness structure and complexity affect the richness of forest and grassland specialist species?

Location

Southeast Sweden.

Methods

We sampled 50 forest edges with different levels of structural complexity in agricultural landscapes. In each border we recorded trees, shrubs and herb layer species in a 50‐m transect parallel with the forest. We investigated species composition and species turnover in relation to the proportions of gaps in the border and the diversity of trees and shrubs.

Results

Total plant species richness in the field layer was mainly explained by the proportion of gaps to areas with full canopy cover and tree diversity. Increasing number of gaps promoted higher diversity of grassland specialist species within the field layer, resulting in open forest borders with the highest overall species richness. Gaps did however have a negative impact on forest species richness. Conversely, increasing forest species richness was positively related to tree diversity, but the number of grassland specialist species was negatively affected by tree diversity.

Conclusions

Managing forest borders, and therefore increasing the area of semi‐open habitats in fragmented agricultural landscapes, provides future opportunities to create a network of suitable habitats for both grassland and deciduous forest specialist species. Such measures therefore have the potential to increase functional connectivity and support dispersal of species in homogeneous forest/agricultural landscapes.     

The Implications of Primate Behavioral Flexibility for Sustainable Human–Primate Coexistence in Anthropogenic Habitats

People are an inescapable aspect of most environments inhabited by nonhuman primates today. Consequently, interest has grown in how primates adjust their behavior to live in anthropogenic habitats. However, our understanding of primate behavioral flexibility and the degree to which it will enable primates to survive alongside people in the long term remains limited. This Special Issue brings together a collection of papers that extend our knowledge of this subject. In this introduction, we first review the literature to identify past and present trends in research and then introduce the contributions to this Special Issue. Our literature review confirms that publications on primate behavior in anthropogenic habitats, including interactions with people, increased markedly since the 2000s. Publications concern a diversity of primates but include only 17% of currently recognized species, with certain primates overrepresented in studies, e.g., chimpanzees and macaques. Primates exhibit behavioral flexibility in anthropogenic habitats in various ways, most commonly documented as dietary adjustments, i.e., incorporation of human foods including agricultural crops and provisioned items, and as differences in activity, ranging, grouping patterns, and social organization, associated with changing anthropogenic factors. Publications are more likely to include information on negative rather than positive or neutral interactions between humans and primates. The contributions to this Special Issue include both empirical research and reviews that examine various aspects of the human–primate interface. Collectively, they show that primate behavior in shared landscapes does not always conflict with human interests, and demonstrate the value of examining behavior from a cost–benefit perspective without making prior assumptions concerning the nature of interactions. Careful interdisciplinary research has the potential to greatly improve our understanding of the complexities of human–primate interactions, and is crucial for identifying appropriate mechanisms to enable sustainable human–primate coexistence in the 21st century and beyond.     

Petunia hybrida CAROTENOID CLEAVAGE DIOXYGENASE7 Is Involved in the Production of Negative and Positive Branching Signals in Petunia

One of the key factors that defines plant form is the regulation of when and where branches develop. The diversity of form observed in nature results, in part, from variation in the regulation of branching between species. Two CAROTENOID CLEAVAGE DIOXYGENASE (CCD) genes, CCD7 and CCD8, are required for the production of a branch-suppressing plant hormone. Here, we report that the decreased apical dominance3 (dad3) mutant of petunia (Petunia hybrida) results from the mutation of the PhCCD7 gene and has a less severe branching phenotype than mutation of PhCCD8 (dad1). An analysis of the expression of this gene in wild-type, mutant, and grafted petunia suggests that in petunia, CCD7 and CCD8 are coordinately regulated. In contrast to observations in Arabidopsis (Arabidopsis thaliana), ccd7ccd8 double mutants in petunia show an additive phenotype. An analysis using dad3 or dad1 mutant scions grafted to wild-type rootstocks showed that when these plants produce adventitious mutant roots, branching is increased above that seen in plants where the mutant roots are removed. The results presented here indicate that mutation of either CCD7 or CCD8 in petunia results in both the loss of an inhibitor of branching and an increase in a promoter of branching.The dynamic process that leads to a plant''s architecture is regulated by developmental factors and by environmental conditions. Whether or not axillary meristems grow to form branches is one key component of plant architecture. Plants with altered architecture have been important in agronomy since the earliest selections were made by humans. More recent examples are vital to the productivity of our current farming systems. The domestication of maize (Zea mays) and the dwarfing of wheat (Triticum aestivum) and rice (Oryza sativa; as part of the Green Revolution) involved alterations to plant height and branch number that dramatically improved productivity (for review, see Sakamoto and Matsuoka, 2004).Arabidopsis (Arabidopsis thaliana), rice, pea (Pisum sativum), and petunia (Petunia hybrida) are important model plants in which axillary branching has been studied. The growth habits of these plants show differences when grown under standard floral inductive conditions. This is due, in part, to the differing developmental programs controlling the outgrowth of axillary branches. Petunia (inbred genetic stock V26) produces basal axillary branches between nodes two and eight that begin their growth during the vegetative growth phase (Snowden and Napoli, 2003). Axillary branches may also form in the nodes immediately below the first flower after the floral transition (Napoli et al., 1999). Arabidopsis generally produces axillary branches after flowering, releasing axillary meristems in the rosette and also from cauline leaves (Hempel and Feldman, 1994). Wild-type, tall pea cultivars such as Parvus are very unlikely to produce basal axillary branches at any stage of growth but do branch at the nodes immediately below the first flower (Stafstrom, 1995). Cultivated rice produces basal axillary branches, called tillers, during vegetative growth. The tillers formed early in plant development will produce panicles (flowering branches), and the remainder will senesce (Hanada, 1993). How these differences in development arise is yet to be understood.Although the overall architecture of plants varies considerably, the genes so far identified that control branching are frequently conserved between species. In particular, two CAROTENOID CLEAVAGE DIOXYGENASE (CCD) genes, CCD7 and CCD8, appear to be well conserved among the plant species studied. Mutations in these two genes result in increased branching phenotypes in every species studied to date (Sorefan et al., 2003; Booker et al., 2004; Snowden et al., 2005; Zou et al., 2005; Johnson et al., 2006; Arite et al., 2007). One interesting line of enquiry is to consider whether differences in the regulation or activity of these two genes are involved in the diversity of architecture seen in plants.Grafting experiments have provided insight into the control of axillary branching, in particular the discovery that signals move from roots to shoots. In petunia, Arabidopsis, and pea, some of the increased branching mutants (ccd7 and ccd8 mutants in particular) can be reverted to a wild-type phenotype by grafting mutant scions onto wild-type rootstocks (for review, see Drummond et al., 2009). Additionally, ccd8 mutant plant lines have been reverted to the wild type by the insertion of a small piece (approximately 2 mm) of wild-type hypocotyl into the hypocotyls of mutant petunia or by insertion of a small piece of epicotyl into the epicotyl of mutant pea (Napoli, 1996; Foo et al., 2001). In Arabidopsis, the ccd7 mutant has been similarly reverted using hypocotyl interstock grafts (Booker et al., 2004). Together, these results suggest the presence of a mobile branch inhibitor produced in wild-type tissue. However, an observation by Napoli (1996) suggested that decreased apical dominance1 (dad1) mutant roots may also have a branch-inducing effect in certain circumstances. A similar result was observed for pea in Parvus by Foo et al. (2001). The discussion presented by Napoli (1996) did not exclude either a branch-inducing or a branch-suppressing signal, although current models generally only consider the presence of a branch inhibitor, and recent efforts have focused on the identification of inhibitors of branching.Strigolactones have recently been identified as signaling molecules that inhibit axillary branch outgrowth in plants (Gomez-Roldan et al., 2008; Umehara et al., 2008). Strigolactones were previously identified as signal molecules secreted from roots. When arbuscular mycorrhizae detect strigolactones, they undergo a preinfection hyperbranching response that is thought to aid fungal colonization of the roots, frequently leading to improved nutrient uptake by the plant (Akiyama et al., 2005). The seeds of the parasitic plants Orobanche species and Striga species are also induced to germinate upon detection of strigolactones in the soil, resulting in significant yield losses for some crops (Cook et al., 1966; Siame et al., 1993; Yokota et al., 1998). The production of strigolactones in rice and pea has been shown to require the action of both CCD7 and CCD8 (Gomez-Roldan et al., 2008; Umehara et al., 2008). The discovery that strigolactones can alter branching confirmed a new layer of regulatory complexity in the control of branching that has long been hidden beneath the global plant growth regulators of auxin and cytokinin.In this study, we have focused on the role of the CCD7 gene in the control of branching in petunia. We have isolated a petunia CCD7 ortholog (PhCCD7) and show that the increased branching phenotype of the dad3 mutant is caused by a lesion in this gene. The phenotype of the dad3 mutant is less severe than that of the petunia ccd8 mutant (dad1), and the double ccd7ccd8 mutant is shown to be additive. These observations are contrasted with what has been observed for other plant species. We show that the regulation of PhCCD7 is similar to that of the PhCCD8 gene, with expression predominantly in root and stem tissue (although at a reduced level) and up-regulation of expression in plants with increased numbers of branches. We also provide evidence for the presence of a branch-promoting signal in mutant roots of petunia. These results suggest that there is an added layer of complexity to the control of branching that is not fully described by current models and indicate that the CCD7 gene may have a role in the diversity of plant architecture.     

"APRIL hath put a spring of youth in everything": Relevance of APRIL for survival

A proliferation inducing ligand (APRIL or TALL-2 and TRDL-1) was first discovered as a cytokine over-expressed in many transformed cells and with the capacity to stimulate proliferation. APRIL was shown to bind two different receptors of the TNF receptor superfamily: B cell maturation antigen (BCMA) and transmembrane activator and calcium modulator and cyclophilin ligand interactor (TACI), as well as heparan sulphate proteoglycans (HSPGs). APRIL has since been shown to play a physiological role in B cell biology, in particular the survival of plasma B cells in a specialized APRIL-rich niche. However, aberrant expression of APRIL and the subsequent activation of pro-survival pathways, is potentially the driving force for the survival of several B cell malignancies. APRIL has therefore become an important therapeutic target, but many questions regarding its mechanism of action still remain. It is for instance unclear what the exact physiological implications of the APRIL-HSPG interaction could be. Neither do we know the precise signals elicited by APRIL in normal or in malignant cells, and whether blocking these effects could provide real therapeutic gain in cancer patients. In this review we discuss the specific relevance of APRIL for cell survival, in terms of both its physiological role and its role in tumor biology, and highlight some of the key questions that will undoubtedly form the basis of future research in this field.     

Discovery of N-propylurea 3-benzylpiperidines as selective CC chemokine receptor-3 (CCR3) antagonists

The discovery of novel and selective small molecule antagonists of the CC Chemokine Receptor-3 (CCR3) is presented. Simple conversion from a 4- to 3-benzylpiperidine gave improved selectivity for CCR3 over the serotonin 5HT(2A) receptor. Chiral resolution and exploration of mono- and disubstitution of the N-propylurea resulted in several 3-benzylpiperidine N-propylureas with CCR3 binding IC(50)s under 5 nM. Data from in vitro calcium mobilization and chemotaxis assays for these compounds ranged from high picomolar to low nanomolar EC(50)s and correlated well with antagonist binding IC(50)s.