Movement of the grape berry moth, Endopiza viteana: displacement distance and direction

Abstract. Mark–release–recapture is used to quantify displacement by adults of the North American grape berry moth, Endopiza viteana Clemens (Lepidoptera: Tortricidae) under field conditions. Moths marked with fluorescent dust are released eight times in the centre of a vineyard over 2 years, and recaptured using pheromone traps and interception traps. In vineyards, male moths are recaptured an average of 13.8 ± 0.8 m from the release site (maximum 58.2 m), whereas female displacement is similar with average flight distances of 11.4 ± 6.7 m (maximum 41.2 m). Increasing wind speed during moth flight activity periods suppresses displacement by both sexes, and females are less likely than males to fly in winds above 0.6 m s^?1. The majority of males are recaptured upwind from the release site or at a tangent to the overall mean wind direction when responding to pheromone traps, whereas female moths trapped in interception traps exhibit a large variability in direction from the release point. Releases of marked moths in woods adjacent to a vineyard demonstrates interhabitat movement by E. viteana males and by a single female. The average maximum displacement by males during interhabitat movement is 105.4 ± 3.9 m, significantly greater than the average maximum of 39.7 ± 6.7 m inside the vineyard habitat.     

Chemotaxis in Vitro: Quantitation of Human Granulocyte Movement Using a Stochastic Differential Equation

The quantitation of human granulocyte movement using a stochastic differential equation is described. The method has the potential to distinguish both positive and negative chemotaxis. Analysis and information concerning cell movements can be obtained for any point in time and distance for the duration of the experiment.     

Trends in biological control: public interest,international networking and research direction

We investigated trends in biological control to both capture its evolution and explore future opportunities. We examined recent changes in public interest, international networking and peer-reviewed research. A Google Trends analysis revealed that the popularity of biological control is decreasing in terms of search hits on the internet. This trend is potentially worrying for the biological control community, given that public interest tends to drive political decisions regarding regulatory processes and governmental funding of research. To examine patterns of international collaboration, we established the list of authors who published their work in the three main biological control journals from the early 1990s to 2016. International co-authorship has intensified and the biological control sector is increasingly characterized by multilateral collaboration. We surveyed papers published in BioControl and Biological Control over the last 25 years to identify research trends with respect to target pests, commodities, biological control agents and biological control approaches. Finally, we report that articles on biological control are published in the broad-based scientific journals Science and Nature on a regular basis. This reflects contributions that biological control research makes to scientific discussions in general. Our analyses revealed a thriving scientific discipline with several major research trends in arthropod, plant pathogen and weed biological control.     

Chemotaxis: Old and New

After describing briefly the work of Engelmann and Pfeffer about 100 years ago, the author presents the early history of bacterial chemotaxis in his laboratory since 1960. Then the report is brought up to the present by review of research in many laboratories including the author's.     

Movement of turritella spermatozoa: direction of propagation and chirality of flagellar bends.

The marine snail, Turritella communis, produces two types of spermatozoa, named apyrene and eupyrene. Eupyrene spermatozoa are usually paired, but unpaired ones are involved in fertilization. Movements of these spermatozoa were analyzed using a video camera with a high-speed shutter. The eupyrene spermatozoa usually swim with the head foremost but are able to swim flagellum foremost. A reversal of the direction of their swimming was found to be the result of a change in the direction of flagellar bend propagation, which changed with calcium concentration. Reversal of the direction of bend propagation was accompanied by a reversal of direction of the rotational movement of the spermatozoa around their long axis, suggesting that the bending waves keep the sense of their three-dimensional form. The swimming speed of apyrene spermatozoa in natural seawater was about one-eighth of that of the eupyrene ones and remained almost constant in highly viscous medium.The swimming speed of conjugated eupyrene spermatozoa was the same as that of unpaired spermatozoa over a wide viscosity range (<3,000 cP). No advantage of swimming by two spermatozoa could be detected in Turritella spermatozoa.     

Chemotaxis and cyclic-di-GMP signalling control surface attachment of Escherichia coli

Attachment to surfaces is an important early step during bacterial infection and during formation of submerged biofilms. Although flagella-mediated motility is known to be important for attachment of Escherichia coli and other bacteria, implications of motility regulation by cellular signalling remain to be understood. Here, we show that motility largely promotes attachment of E. coli, including that mediated by type 1 fimbriae, by allowing cells to reach, get hydrodynamically trapped at and explore the surface. Inactivation or inhibition of the chemotaxis signalling pathway improves attachment by suppressing cell reorientations and thereby increasing surface residence times. The attachment is further enhanced by deletion of genes encoding the cyclic diguanosine monophosphate (c-di-GMP)-dependent flagellar brake YcgR or the diguanylate cyclase DgcE. Such increased attachment in absence of c-di-GMP signalling is in contrast to its commonly accepted function as a positive regulator of the sessile state. It is apparently due to the increased swimming speed of E. coli in absence of YcgR-mediated motor control, which strengthens adhesion mediated by the type 1 fimbriae. Thus, both signalling networks that regulate motility of E. coli also control its engagement with both biotic and abiotic surfaces, which has likely implications for infection and biofilm formation.     

Chemotaxis: signalling the way forward

During random locomotion, human neutrophils and Dictyostelium discoideum amoebae repeatedly extend and retract cytoplasmic processes. During directed cell migration--chemotaxis--these pseudopodia form predominantly at the leading edge in response to the local accumulation of certain signalling molecules. Concurrent changes in actin and myosin enable the cell to move towards the stimulus. Recent studies are beginning to identify an intricate network of signalling molecules that mediate these processes, and how these molecules become localized in the cell is now becoming clear.     

Amoeboid Chemotaxis

Chemotaxis is the directed movement of a cell towards a gradient of chemicals such as chemokines or growth factors. This phenomenon can be studied in organisms ranging from bacteria to mammalian cells and here we will focus on eukaryotic amoeboid chemotaxis. Chemotactic responses are mediated by two major classes of receptors: GPCR’s and RTK’s, with multiple pathways signaling downstream of them, certain ones functioning in parallel. In this review we address two important features of amoeboid chemotaxis that will be important for further advances in the field. First, the application of in vivo imaging will be critical for providing insight into the functional requirements for chemotactic responses. We will briefly cover a number of systems in which in vivo imaging is providing new insights. Second, due to the network-type design of signaling pathways of eukaryotic chemotaxis, more refined phenotypic analysis will be necessary, and we will discuss recent analyses of the role of the phosphoinositide 3-kinase pathway in this light. We will close with some speculations regarding future applications of more detailed in vivo analysis and mechanistic understanding of eukaryotic amoeboid chemotaxis.     

Chemotaxis, signal relaying and aggregation morphology

It is shown that a system of cells which are attracted by chemotaxis to a signal released by themselves can aggregate (in the form of delta function concentrations). This aggregation is initiated by random fluctuations which occur naturally. When the signalling is cooperative, such an aggregation presents a characteristic streaming morphology, observed in some of the cellular slime moulds.     

Chemotaxis: TorC before you Akt..

Chemotaxis uses intertwined signalling pathways, each individually dispensable. Recent work shows that Dictyostelium PKB/Akt can be spatially regulated independently of phosphatidylinositol (3,4,5)-trisphosphate via phosphorylation by TOR complex 2, placing this complex at the hub of chemotaxis.     

Mechanisms of Gradient Sensing and Chemotaxis: Conserved Pathways,Diverse Regulation

Directed cell migration is critical for normal development, immune responses, and wound healing and plays a prominent role in tumor metastasis. In eukaryotes, cell orientation is biased by an external chemoattractant gradient through a spatial contrast in chemoattractant receptor-mediated signal transduction processes that differentially affect cytoskeletal dynamics at the cell front and rear. Mechanisms of spatial gradient sensing and chemotaxis have been studied extensively in the social amoeba Dictyostelium discoideum and mammalian leukocytes (neutrophils), which are similar in their remarkable sensitivity to shallow gradients and robustness of response over a broad range of chemoattractant concentration. Recently, we have quantitatively characterized a different gradient sensing system, that of platelet-derived growth factor-stimulated fibroblasts, an important component of dermal wound healing. The marked differences between this system and the others have led us to speculate on the diversity of gradient sensing mechanisms and their biological implications.     

Chemotaxis: Cofilin in the driver's seat

A cell responds to a chemotactic signal by activating actin polymerization and forming a protrusion oriented towards the source. Recent work shows that the activity of cofilin, a protein that creates new barbed ends for actin filament elongation, amplifies and specifies the direction of the response in carcinoma cells.     

Amoeboid Chemotaxis: Future Challenges and Opportunities

Chemotaxis is the directed movement of a cell towards a gradient of chemicals such as chemokines or growth factors. This phenomenon can be studied in organisms ranging from bacteria to mammalian cells, and here we will focus on eukaryotic amoeboid chemotaxis. Chemotactic responses are mediated by two major classes of receptors: GPCR''s and RTK''s, with multiple pathways signaling downstream of them, certain ones functioning in parallel. In this review we address two important features of amoeboid chemotaxis that will be important for further advances in the field. First, the application of in vivo imaging will be critical for providing insight into the functional requirements for chemotactic responses. We will briefly cover a number of systems in which in vivo imaging is providing new insights. Second, due to the network-type design of signaling pathways of eukaryotic chemotaxis, more refined phenotypic analysis will be necessary, and we will discuss recent analyses of the role of the phosphoinositide 3-kinase pathway in this light. We will close with some speculations regarding future applications of more detailed in vivo analysis and mechanistic understanding of eukaryotic amoeboid chemotaxis.Key Words: chemotaxis, signaling, in vivo models, development, phospholipase, phosphoinositide 3-kinase     

Chemotaxis in Actinoplanes

The chemotactic properties of spores of Actinoplanes brasiliensis were examined. The spores are attracted to chloride and bromide solutions but not to a number of organic compounds that are capable of supporting growth in chemically defined media. Chloride attraction has been tested in several other species of the genus and in a number of Actinoplanes strains isolated from soils. Some are attracted to chloride, but most strains are indifferent to the halide. In dense suspensions, the spores of A. brasiliensis show an apparent microaerophilic behavior. The ecological implications of the chemotactic properties of the A. brasiliensis spores are discussed.Dedicated to Professor R. Y. Stanier on the occasion of his 60th birthday