Migratory Tracks Research Articles

Extremely detoured migration in an inexperienced bird: interplay of transport costs and social interactions

We tagged two juvenile short-toed eagles in southern Italian peninsula with GPS satellite transmitters. According to previous visual observations, two different migratory routes for Italian short-toed eagles to reach Africa in autumn have been proposed: via Sicily and via Gibraltar. These routes include different over-water distances to cross the Mediterranean Sea, and thus different proportions of flight modes (soaringgliding vs flappinggliding) with resulting different transport costs. Considering different scenarios of energy cost of transport, with flapping-gliding flight over water being more costly than flying over land using soaringgliding flight, we predicted a maximum optimal detour of 1218 km. Both individuals reached Africa using the longest, detoured, route, avoiding the longest water crossing. To achieve this they began migrating northwards, keeping for ca 700 km a direction opposite to that followed by any other migrating bird from the Northern hemisphere in autumn. The comparison of optimal detour predictions with observed migratory tracks suggests that this migratory strategy prioritizes not only energy minimization, but also safety, given the mortality risk associated with the sea crossing. Finally, it is unlike that these inexperienced individuals followed such a complex route relying only on endogenous information and we therefore suggest, also on the basis of field observations, that social interactions (adult guidance) allow these individuals to learn the detoured route.

Probing the mystery of Chinese medicine meridian channels with special emphasis on the connective tissue interstitial fluid system, mechanotransduction, cells durotaxis and mast cell degranulation.

This article hypothesizes that the Chinese medicine meridian system is a special channel network comprising of skin with abundant nerves and nociceptive receptors of various types, and deeper connective tissues inside the body with the flowing interstitial fluid system. These meridian channels provide efficient migratory tracks mainly due to durotaxis (also including chemotaxis) for mast cells, fibroblasts and other cells to migrate and carry out a number of physiological functions. Acupuncture acting on meridian channel causes cytoskeletal remodeling through mechanotransduction, leading to regulation of gene expression and the subsequent production of related proteins. Also, stimulation on cell surface can trigger Ca2+ activities, resulting in a cascade of intra- and inter-cellular signaling. Moreover, nerve endings in the meridian channels interact with mast cells and induce the degranulation of these cells, leading to the release of many specific biomolecules needed for homeostasis, immune surveillance, wound healing and tissue repair. Acupoint along a meridian channel is a functional site to trigger the above functions with specificity and high efficiency.

Reconstruction of Zebrafish Early Embryonic Development by Scanned Light Sheet Microscopy

A long-standing goal of biology is to map the behavior of all cells during vertebrate embryogenesis. We developed digital scanned laser light sheet fluorescence microscopy and recorded nuclei localization and movement in entire wild-type and mutant zebrafish embryos over the first 24 hours of development. Multiview in vivo imaging at 1.5 billion voxels per minute provides "digital embryos," that is, comprehensive databases of cell positions, divisions, and migratory tracks. Our analysis of global cell division patterns reveals a maternally defined initial morphodynamic symmetry break, which identifies the embryonic body axis. We further derive a model of germ layer formation and show that the mesendoderm forms from one-third of the embryo's cells in a single event. Our digital embryos, with 55 million nucleus entries, are provided as a resource.

Recherches méthodologiques pour la typologie de la végétation et la phytogéographie des forêts denses d'Afrique tropicale

Click to increase image sizeClick to decrease image sizeKey-words: phytosociologyopen classificationzonalnon-zonalnested plotssubmontanealtitudinal beltscontinentalityEquatorial GuineaMonte Alénforest stratumunderstoreyplant functional typesarchitectural modelsbiodiversityglacial refugeMots-clés: phytosociologieclassifications ouverteszonalazonalrelevésemboîtéssubmontagnardétages d'altitudecontinentalitéGuinée EquatorialeMonte Alénstrate forestièresous-boistypes fonctionnelsmodèles architecturauxbiodiversitérefuge glaciaire

Migrations and foraging of juvenile southern elephant seals from Macquarie Island within CCAMLR managed areas

Twenty-three juvenile (8–14 months of age) southern elephant seals (Mirounga leonina L.) from Macquarie Island were tracked during 1993 and 1995. Migratory tracks and ocean areas with concentrated activity, presumed to be foraging grounds, were established from location data gathered by attached geolocation-time depth recorders. The seals ranged widely (811–3258 km) and foraging activity centred on oceanographic frontal systems, especially the Antarctic Polar Front and bathymetric features such as the Campbell Plateau region. The seals spent 58.6% of their sea time within managed fishery areas while the remainder was spent on the high seas, an area of unregulated fishing. The Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR) areas 58.4.1, 88.2 and especially 88.1 were important and distant foraging areas for these juvenile elephant seals. From fisheries records, diet and the foraging ecology studies of the seals there appears to be little, if any, overlap or conflict between the seals and commercial fishing operations within the regulated commercial areas. However, attention is drawn to the possibility of future interactions if Southern Ocean fisheries expand or new ones commence.

Neural progenitors from human embryonic stem cells.

The derivation of neural progenitor cells from human embryonic stem (ES) cells is of value both in the study of early human neurogenesis and in the creation of an unlimited source of donor cells for neural transplantation therapy. Here we report the generation of enriched and expandable preparations of proliferating neural progenitors from human ES cells. The neural progenitors could differentiate in vitro into the three neural lineages--astrocytes, oligodendrocytes, and mature neurons. When human neural progenitors were transplanted into the ventricles of newborn mouse brains, they incorporated in large numbers into the host brain parenchyma, demonstrated widespread distribution, and differentiated into progeny of the three neural lineages. The transplanted cells migrated along established brain migratory tracks in the host brain and differentiated in a region-specific manner, indicating that they could respond to local cues and participate in the processes of host brain development. Our observations set the stage for future developments that may allow the use of human ES cells for the treatment of neurological disorders.

Diving behavior of juvenile northern elephant seals

We describe and review the development of the diving and foraging pattern of northern elephant seals, Mirounga angustirostris, during migrations over the first 2 years of life. The diving pattern and migratory tracks of 23 juveniles, 9–27 months of age, from Año Nuevo and Piedras Blancas, California, were recorded with attached time–depth recorders and Argos satellite tags. The seals exhibited a general diving pattern like that of adults, diving deep (373 ± 77 m per dive (mean ± SD)), long (15.2 ± 2.6 min per dive), and continuously (88.7 ± 2.7% of the time submerged while at sea). Level of performance increased with age and experience up to 2 years of age, the end of the fourth migration, when modal diving performance was equal to that of adults. Juveniles migrated north to the waters west of Oregon, Washington, and British Columbia, moving more slowly and not as far as adults. By the third trip to sea, males began to exhibit more flat-bottomed dives than females, a sex difference observed in adults, suggesting that males supplement a diet of pelagic organisms with benthic prey. These data and related observations of elephant seals suggest that the greatest physiological changes enabling an animal to dive occur near the rookery following weaning, before the first trip to sea; transition to a pelagic existence is difficult, as reflected by high mortality during the first migration; improvement of diving skills continues up to 2 years of age; and sex differences in foraging behavior and foraging location, similar to those seen in adults, are evident before the seals reach 2 years of age.

Cranial nerve growth in birds is preceded by cholinesterase expression during neural crest cell migration and the formation of an HNK-1 scaffold

The expression of the neural crest cell (NCC) markers acetylcholinesterase (AChE) and the HNK-1-epitope is compared from the emigration of cephalic NCC until the formation of the cranial nerves V-X in chicken and quail hindbrain. We show that NCC transiently express acetylcholinesterase (AChE) activity during their emigration; NCC migrate into butyrylcholinesterase (BChE)-positive areas of the cranial mesenchyme. Along these migratory tracks that foreshadow the course of later projecting cranial nerves, BChE increases strongly in cells that may represent immature Schwann cells. Both AChE and BChE, but not HNK-1, are expressed in the ectodermal placodes. In NCC, HNK-1 is expressed strongly only when they approach their destination sites. Their intense expression of HNK-1 then leads to the establishment of tunnel-shaped HNK-1 matrices, within which G4-positive cranial neurites begin to extend. We conclude that AChE and HNK-1 expression in cephalic NCC serve different functions, since AChE is related to their migration, and HNK-1 to their aggregation and the formation of an extracellular neurite scaffold.

USE OF ALBENDAZOLE IN FEED TO CONTROL FASCIOLOIDES MAGNA INFECTIONS IN CAPTIVE WHITE-TAILED DEER (ODOCOILEUS VIRGINIANUS)

Thirty-six adult white-tailed deer (Odocoileus virginianus) naturally infected with Fascioloides magna were captured and randomly assigned to four groups. Each group was fed pelleted feed coated with albendazole for each of seven consecutive days to deliver the drug at a dose rate of approximately 0.0, 5.0, 8.5, or 16.5 mg/kg bodyweight/day. At 7 wk posttreatment, each animal was euthanized and necropsied. Effects of albendazole treatment included significant reduction (P less than 0.05) in parasite egg count per gram of feces and increase in serum albumin concentration (P less than 0.05). Smaller parasites or remains of dead parasites were seen at the end of migratory tracks in the treated groups. Efficacy of the drug was 82 to 84%.

Taenia taeniaeformis (Cestoda) in the Rat: Ultrastructure of the Host-Parasite Interface on Days 8 to 22 Postinfection

Ultrastructural observation were made on the host-parasite interface from 1 to 7 days postinfection (DPI) with Taenia taeniaeformis in the rat. Over this period the organism developed from a multicellular oncospheral mass, equivalent in size to a host hepatocyte, into a fluid-filled, grossly visible vesicle, the walls of which showed the arrangement of syncytial tegument, cytoplasmic bridges and subtegumental cell bodies typical of older cestodes. Microvilli, often branched, extended from the free, tegumental surface of the parasite from 1 DPI onwards. Fragments of the microvilli were pinched off distally, and became segmented and distended. Some were seen in intercellular spaces as far as 40 micrometers from the free tegumental surface; others were ingested by nearby host phagocytic cells, and appeared to swell and rupture within phagosomes. Microvillar branching was less frequent after 4 DPI and the microvilli became progressively shorter. By 7 DPI the tegumental surface had become irregular and the microvillar bases were broad and knoblike. Electron-dense deposits were present on the outer membrane of microvilli, the tips of which had become truncated or globular. Although phagocytic host cells were seen in migratory tracks and in contact with some organisms as early as 1 DPI, they caused no detectable damage to the parasites. However, many host cells, including hepatocytes and endothelial cells, were injured or destroyed; their contents contributed to the debris surrounding the parasite at all stages. Inclusions, probably lipid, appeared within the tegument and subtegumental cell bodies from 3 DPI onwards, and similar droplets were seen in adjacent host cells. The great increase in surface area of postoncospheral forms over the first week of infection, augmented by the display of multiple, microvillar projections, may provide not only or the absorption of nutrients required for growth, but also for the enhanced release of factors that affect survival of host cells and stimulate immunological defense mechanisms.

Age-associated responses in susceptible and resistant rats to infection with Fasciola hepatica

Rajasekariah G. R. and Howell M. J. 1981. Age-associated responses in susceptible and resistant rats to infection with Fasciola hepatica. International Journal for Parasitology 11: 59–65. Groups of susceptible (5-week-old) and age resistant (25-week-old) outbred male Wistar rats were infected with metacercariae of Fasciola hepatica and the establishment of the parasite was assessed in terms of worm reocvery, and haematological, histopathological and immunological criteria, 2, 4, 6 and 8 weeks after infection. Apart from 2 weeks after infection, there was a significant difference between groups in the recovery of F. hepatica, with resistant rats infected with consistently fewer parasites than susceptible animals. The juvenile worms which invaded the livers of resistant rats elicited a number of host reactions, marked by an intensive cellular infiltration into migratory tracks of the parasite, heavy deposition of fibrous tissue in the liver parenchyma and a rapid antibody response. These responses were not as striking in susceptible animals even though more worms were present. The ability of resistant rats to mount an enhanced response seems related to the maturation of their haemopoietic system.

Studies on the Pathology of Dicrocoeliasis and Fascioliasis in the Goat I. The Histopathology of the Liver and Bile Ducts

Comparative studies were made on the histopathology of the liver and bile ducts in dicrocoeliasis and fascioliasis of the goat. Investigations revealed certain similarities in the nature of the pathological phenomena produced by D. dendriticum and F. hepatica. However, a feature peculiar to fascioliasis was the migratory tracks of immature flukes in the liver parenchyma. Further, the lesions produced by fascioliasis were distinctly more pronounced than those present in dicrocoeliasis. In both parasitic diseases the bile-duct walls showed glandular hyperplasia, increased frequency of goblet cells and globule leucocytes, and extensive fibrosis in the outer layers. The desquamation produced by Dicrocoelium remained superficial whereas Fasciola was capable of causing deep erosions in the walls of the main bile ducts. The bile-duct walls did not become calcified. Increased fibrosis was present in the interlobular areas, too, but only fascioliasis produced extensive disorganisation of the hepatic architecture, due to the scars originating from repaired migratory tracks. The liver parenchymal cells were degenerated, showed decreased glycogen but were increasingly infiltrated by neutral fats.

Fluorescence ophthalmoscopy.

<h3>Introduction</h3> Statin use in COPD is associated with a reduction in all cause mortality, with greatest reductions seen in patients with the highest inflammatory burden. However, the mechanism for these effects is poorly understood, as statin treatment has not been found to lower systemic inflammation and <i><i>in vitro</i></i>studies of cellular effects use concentrations that exceed the therapeutic range. Neutrophils are key effector cells in COPD, and correlate with disease severity and inflammation. Recent <i>in vitro</i> studies have shown neutrophil migratory accuracy to be reduced in COPD. This is thought to contribute to the destruction of lung parenchyma and the poor responses seen in infective exacerbations. We aimed to characterise neutrophil migration in COPD and assess whether physiologically relevant concentrations of simvastatin altered neutrophil migration. <h3>Methods</h3> Neutrophils were isolated from COPD patients and healthy smoking age-matched controls (age &gt; 60yrs, n = 13 per group) and incubated with 1nM - 1μM Simvastatin or with a carrier control before migratory dynamics were assessed towards IL8 and fMLP using time-lapse photography. Data is expressed as means with standard deviation in parentheses. <h3>Results</h3> COPD neutrophils displayed reduced chemotaxis (directional speed of migration) and reduced chemotactic accuracy (Chemotactic Index - a vector analysis of migratory tracks) compared to cells from healthy age-matched controls (HC) in the presence of IL-8 and f-MLP, replicating previous work. For example, Chemotactic Index: IL8; HC, 0.42CU (0.03), COPD 0.22CU (0.05), p = 0.002: fMLP; HC, 0.34CU (0.05), COPD, 0.18CU (0.03) p = 0.014). Treatment with Simvastatin significantly improved the chemotactic ability of COPD neutrophils in a dose response with greatest improvement seen at the highest concentration (e.g. Chemotaxis to IL8, Carrier control 0.8um/min (0.2), 1nM Simvastatin 1.3um/min (0.2), p = 0.04; 1uM Simvastatin 1.4um/min (0.2), p = 0.004). A similar improvement was seen in Chemotactic Accuracy (e.g. Chemotactic Index to fMLP, Carrier control 0.17CU (0.03), 1nM Simvastatin 0.26CU (0.02), p = 0.018; 1uM Simvastatin 0.31CU (0.03), p = 0.002). <h3>Conclusions</h3> Migratory accuracy of circulating neutrophils is reduced in COPD patients compared with healthy, smoking, age-matched controls but can be restored by treatment with therapeutic concentrations of Simvastatin <i><i>in vitro</i></i>. Our data suggest statin therapy might be an adjuvant intervention in COPD, modulating neutrophil responses.