Beautiful,complicated—and intelligent? Novel aspects of the thigmonastic stamen movement in Loasaceae

In a recent study we investigated the complex mechanisms regulating the pollen release via thigmonastic stamen movement found exclusively in Loasaceae subfamily Loasoideae. We demonstrated that stamen movement is modulated by abiotic (light and temperature) as well as biotic stimuli (pollinator availability and visitation frequency). This is explained as a mechanism to adjust the rate of stamen movement and thus pollen dispensation to different environmental conditions in order to optimize pollen transfer. Stamen movement is rapid and thus a near-immediate response to pollinator visits. However, Loasaceae flowers also show a response to biotic stimuli on a longer time scale, by adjusting the duration of both the staminate and the carpellate phase of the anthesis. We here present two additional data sets on species not previously studied, underscoring the shortening of the staminate phase in the presence of pollinator visits vs. their absence and the shortening of the carpellate phase after pollination. Overall, the plant shows not only a rapid but an “intelligent” reaction to its environment in adjusting anthesis and pollen presentation to a range of factors. The physiological and morphological bases of the stamen movement are poorly understood. Our previous study showed that there is no direct spatial relationship between the place of stimulation in the flower and the stamen bundle activated. We here further show the morphological basis for stamen movement from a reflexed into an erect position: Only the basal part of the filament curves around the receptacle, while the upper part of the filament retains its shape. We hypothesize that the stimulus is transmitted over the entire receptacle and the place of reaction is determined by stamen maturity, not the location of the stimulus.     

干细胞在牙齿再生研究中的应用

干细胞是一类能够自我更新并分化形成多种组织细胞类型的原始细胞.基于其特殊的生物学性质,干细胞可作为器官再生的理想种子细胞.干细胞已成功被诱导为神经、心肌、皮肤、软骨、肝脏、胰岛、造血等不同类型组织细胞,为神经损伤、退行性变、胰岛素依赖性糖尿病、造血功能障碍等多种难活性疾病提供替代疗法.牙齿是人体中唯一的能在成体中再次发育而且结构相对简单的一个器官,因此牙齿再生已成为组织工程研究领域的热点.目前,在模式动物小鼠以及小型猪中已开展许多利用干细胞进行釉质、本质、牙髓以及牙周韧带等牙齿组织再生和整牙再生的研究.本文系统地概括了不同来源的干细胞(胚胎干细胞、成体干细胞和诱导多能干细胞)在牙齿再生研究中的应用.其中,成体干细胞具有来源广泛、便于采集培养以及不导入外源基因等优势,在牙齿再生的基础研究和临床应用中具有更大的价值.     

Linking behavioral states to landscape features for improved conservation management

1. A central theme for conservation is understanding how animals differentially use, and are affected by change in, the landscapes they inhabit. However, it has been challenging to develop conservation schemes for habitat‐specific behaviors.
2. Here we use behavioral change point analysis to identify behavioral states of golden eagles (Aquila chrysaetos) in the Sonoran and Mojave Deserts of the southwestern United States, and we identify, for each behavioral state, conservation‐relevant habitat associations.
3. We modeled behavior using 186,859 GPS points from 48 eagles and identified 2,851 distinct segments comprising four behavioral states. Altitude above ground level (AGL) best differentiated behavioral states, with two clusters of short‐distance movement behaviors characterized by low AGL (state 1 AGL = 14 m (median); state 2 AGL = 11 m) and two associated with longer‐distance movement behaviors and characterized by higher AGL (state 3 AGL = 108 m; state 4 AGL = 450 m).
4. Behaviors such as perching and low‐altitude hunting were associated with short‐distance movements in updraft‐poor environments, at higher elevations, and over steeper and more north‐facing terrain. In contrast, medium‐distance movements such as hunting and transiting were over gentle and south‐facing slopes. Long‐distance transiting occurred over the desert habitats that generate the best updraft.
5. This information can guide management of this species, and our approach provides a template for behavior‐specific habitat associations for other species of management concern.

     

Pelagic seabird flight patterns are consistent with a reliance on olfactory maps for oceanic navigation

Homing studies have provided tantalizing evidence that the remarkable ability of shearwaters (Procellariiformes) to pinpoint their breeding colony after crossing vast expanses of featureless open ocean can be attributed to their assembling cognitive maps of wind-borne odours but crucially, it has not been tested whether olfactory cues are actually used as a system for navigation. Obtaining statistically important samples of wild birds for use in experimental approaches is, however, impossible because of invasive sensory manipulation. Using an innovative non-invasive approach, we provide strong evidence that shearwaters rely on olfactory cues for oceanic navigation. We tested for compliance with olfactory-cued navigation in the flight patterns of 210 shearwaters of three species (Cory''s shearwaters, Calonectris borealis, North Atlantic Ocean, Scopoli''s shearwaters, C. diomedea Mediterranean Sea, and Cape Verde shearwaters, C. edwardsii, Central Atlantic Ocean) tagged with high-resolution GPS loggers during both incubation and chick rearing. We found that most (69%) birds displayed exponentially truncated scale-free (Lévy-flight like) displacements, which we show are consistent with olfactory-cued navigation in the presence of atmospheric turbulence. Our analysis provides the strongest evidence yet for cognitive odour map navigation in wild birds. Thus, we may reconcile two highly disputed questions in movement ecology, by mechanistically connecting Lévy displacements and olfactory navigation. Our approach can be applied to any species which can be tracked at sufficient spatial resolution, using a GPS logger.     

Plasmodesmata‐located protein overexpression negatively impacts the manifestation of systemic acquired resistance and the long‐distance movement of Defective in Induced Resistance1 in Arabidopsis

Systemic acquired resistance (SAR) is a plant defence response that provides immunity to distant uninfected leaves after an initial localised infection. The lipid transfer protein (LTP) Defective in Induced Resistance1 (DIR1) is an essential component of SAR that moves from induced to distant leaves following a SAR‐inducing local infection. To understand how DIR1 is transported to distant leaves during SAR, we analysed DIR1 movement in transgenic Arabidopsis lines with reduced cell‐to‐cell movement caused by the overexpression of Plasmodesmata‐Located Proteins PDLP1 and PDLP5. These PDLP‐overexpressing lines were defective for SAR, and DIR1 antibody signals were not observed in phloem sap‐enriched petiole exudates collected from distant leaves. Our data support the idea that cell‐to‐cell movement of DIR1 through plasmodesmata is important during long‐distance SAR signalling in Arabidopsis.     

Rice stripe tenuivirus p2 may recruit or manipulate nucleolar functions through an interaction with fibrillarin to promote virus systemic movement

Rice stripe virus (RSV) is the type species of the genus Tenuivirus and represents a major viral pathogen affecting rice production in East Asia. In this study, RSV p2 was fused to yellow fluorescent protein (p2‐YFP) and expressed in epidermal cells of Nicotiana benthamiana. p2‐YFP fluorescence was found to move to the nucleolus initially, but to leave the nucleolus for the cytoplasm forming numerous distinct bright spots there at later time points. A bimolecular fluorescence complementation (BiFC) assay showed that p2 interacted with fibrillarin and that the interaction occurred in the nucleus. Both the nucleolar localization and cytoplasmic distribution of p2‐YFP fluorescence were affected in fibrillarin‐silenced N. benthamiana. Fibrillarin depletion abolished the systemic movement of RSV, but not that of Tobacco mosaic virus (TMV) and Potato virus X (PVX). A Tobacco rattle virus (TRV)‐based virus‐induced gene silencing (VIGS) method was used to diminish RSV NS2 (encoding p2) or NS3 (encoding p3) during RSV infection. Silencing of NS3 alleviated symptom severity and reduced RSV accumulation, but had no obvious effects on virus movement and the timing of symptom development. However, silencing of NS2 abolished the systemic movement of RSV. The possibility that RSV p2 may recruit or manipulate nucleolar functions to promote virus systemic infection is discussed.     

Larval dispersal and movement patterns of coral reef fishes,and implications for marine reserve network design

Well‐designed and effectively managed networks of marine reserves can be effective tools for both fisheries management and biodiversity conservation. Connectivity, the demographic linking of local populations through the dispersal of individuals as larvae, juveniles or adults, is a key ecological factor to consider in marine reserve design, since it has important implications for the persistence of metapopulations and their recovery from disturbance. For marine reserves to protect biodiversity and enhance populations of species in fished areas, they must be able to sustain focal species (particularly fishery species) within their boundaries, and be spaced such that they can function as mutually replenishing networks whilst providing recruitment subsidies to fished areas. Thus the configuration (size, spacing and location) of individual reserves within a network should be informed by larval dispersal and movement patterns of the species for which protection is required. In the past, empirical data regarding larval dispersal and movement patterns of adults and juveniles of many tropical marine species have been unavailable or inaccessible to practitioners responsible for marine reserve design. Recent empirical studies using new technologies have also provided fresh insights into movement patterns of many species and redefined our understanding of connectivity among populations through larval dispersal. Our review of movement patterns of 34 families (210 species) of coral reef fishes demonstrates that movement patterns (home ranges, ontogenetic shifts and spawning migrations) vary among and within species, and are influenced by a range of factors (e.g. size, sex, behaviour, density, habitat characteristics, season, tide and time of day). Some species move <0.1–0.5 km (e.g. damselfishes, butterflyfishes and angelfishes), <0.5–3 km (e.g. most parrotfishes, goatfishes and surgeonfishes) or 3–10 km (e.g. large parrotfishes and wrasses), while others move tens to hundreds (e.g. some groupers, emperors, snappers and jacks) or thousands of kilometres (e.g. some sharks and tuna). Larval dispersal distances tend to be <5–15 km, and self‐recruitment is common. Synthesising this information allows us, for the first time, to provide species, specific advice on the size, spacing and location of marine reserves in tropical marine ecosystems to maximise benefits for conservation and fisheries management for a range of taxa. We recommend that: (i) marine reserves should be more than twice the size of the home range of focal species (in all directions), thus marine reserves of various sizes will be required depending on which species require protection, how far they move, and if other effective protection is in place outside reserves; (ii) reserve spacing should be <15 km, with smaller reserves spaced more closely; and (iii) marine reserves should include habitats that are critical to the life history of focal species (e.g. home ranges, nursery grounds, migration corridors and spawning aggregations), and be located to accommodate movement patterns among these. We also provide practical advice for practitioners on how to use this information to design, evaluate and monitor the effectiveness of marine reserve networks within broader ecological, socioeconomic and management contexts.     

Turnip vein clearing virus movement protein nuclear activity: Do Tobamovirus movement proteins play a role in immune response suppression?

Plant viruses'' cell-to-cell movement requires the function of virally encoded movement proteins (MPs). The Tobamovirus, Tobacco mosaic virus (TMV) has served as the model virus to study the activities of single MPs. However, since TMV does not infect the model plant Arabidopsis thaliana I have used a related Tobamovirus, Turnip vein-clearing virus (TVCV). I recently showed that, despite belonging to the same genus, the behavior of the 2 viruses MPs differ significantly during infection. Most notably, MP^TVCV, but not MP^TMV, targets the nucleus and induces the formation of F actin-containing filaments that associate with chromatin. Mutational analyses showed that nuclear localization of MP^TVCV was necessary for TVCV local and systemic infection in both Nicotiana benthamiana and Arabidopsis. In this addendum, I propose possible targets for the MP^TVCV nuclear activity, and suggest viewing MPs as viral effector-like proteins, playing a role in the inhibition of plant defense.