The structure and mode of action of the posterior adhesive organ of Pseudobenedenia nototheniae Johnston, 1931 (Monogenea: Capsaloidea)

Parasitology ◽  
1973 ◽  
Vol 66 (3) ◽  
pp. 473-485 ◽  
Author(s):  
I. C. Williams ◽  
C. Ellis ◽  
V. W. Spaull
Keyword(s):  
Surface Area ◽  
Water Flow ◽  
Mode Of Action ◽  
Pressure Difference ◽  
Close Contact ◽  
Ventral Surface ◽  
Orkney Islands ◽  
South Orkney Islands ◽  
Adhesive Organs ◽  
Central Loculus

An account is given of the structure and mode of action of the opisthaptor of the monogenean Pseudobenedenia nototheniae Johnston, 1931, from the skin of the fish Notothenia neglecta, caught in December 1969 at a depth of 40 m offSigny Island (60° 43′ S., 45° 36′ W.), South Orkney Islands. The opisthaptor has a roughly hexagonal central loculus surrounded by a septum which is continuous with six radiating septa. It is armed with 14 marginal hooklets and three pairs of sclerites which function as anchors. The opisthaptor obtains adhesion through gripping the host's skin with the muscular rim, and through close contact by the marginal membrane. These form a water-tight seal, the surface area of which is about one-quarter of that of the ventral surface of the opisthaptor. The seal enables the opisthaptor to function as an underwater sucker. Contraction of muscles associated with the opisthaptor, in particular the extrinsic muscles, can generate a pressure difference across the wall of the opisthaptor some 50 times greater than that required to support the weight of the parasite, thus suggesting that reserves are available to resist dislodging forces such as increased water flow. The instability and tendency to slide of the sucker is counteracted by anchorage from the hooklets and sclerites. The structure and mode of action of the opisthaptor of P. nototheniae are discussed in relation to studies made by other authors on similar adhesive organs.

scholarly journals The climbing organ of an insect, Rhodnius prolixus (Hemiptera; Reduviidœ)

1932 ◽  
Vol 111 (772) ◽  
pp. 364-376 ◽  
Keyword(s):  
Mode Of Action ◽  
Ventral Surface ◽  
Rhodnius Prolixus ◽  
Blood Sucking ◽  
New Type

Adhesive or climbing organs are familiar structures in many groups of insects. Most commonly, as in Hymenoptera, Diptera and many Hemiptera, they take the form of empodia or pulvilli between the tarsal claws; in a few Hemiptera they occur at the lower end of the tibia (Weber, 1930), while in many Coleoptera and Orthoptera it is the ventral surface of the tarsal segments themselves which is specially modified (Dewitz, 1884). These structure are generally stated to be absent in the Reduviidæ, but one of us (Gillett, 1932) has recently observed a new type of climbing organ in the blood-sucking reduviid bug, Rhodnius prolixus stål. The object of the present paper is to describe the structure of this organ and to discuss its mode of action.

scholarly journals Identification of marine Important Bird and Biodiversity Areas for penguins around the South Shetland Islands and South Orkney Islands

2018 ◽  
Vol 8 (21) ◽  
pp. 10520-10529 ◽  
Author(s):  
Maria P. Dias ◽  
Ana Paula Bertoldi Carneiro ◽  
Victoria Warwick-Evans ◽  
Colin Harris ◽  
Katharina Lorenz ◽  
...  
Keyword(s):  
South Shetland Islands ◽  
The South ◽  
Shetland Islands ◽  
Orkney Islands ◽  
South Orkney Islands

scholarly journals The Scottish National Antarctic Expedition, 1902–1904: reconstructing the missing geological report

2018 ◽  
Vol 45 (2) ◽  
pp. 350-362 ◽  
Author(s):  
Philip Stone
Keyword(s):  
Research Programme ◽  
Medical Doctor ◽  
Scientific Investigation ◽  
Orkney Islands ◽  
Unpublished Work ◽  
Antarctic Expedition ◽  
South Orkney Islands ◽  
Scientific Results ◽  
Quality Reports ◽  
Archive Material

The Scottish National Antarctic Expedition (1902–1904) made the first topographical survey and scientific investigation of Laurie Island, one of the South Orkney Islands, and completed an extensive oceanographical research programme in the Scotia and Weddell Seas. When the expedition returned to Scotland, the leader, William Speirs Bruce, embarked on an ambitious attempt to publish the expedition's scientific results in a series of high-quality reports. Sadly, by the time it came to the eighth volume (on geology) his funds were exhausted, and the series was abandoned. Nevertheless, many of the contributions that had been intended for that volume were produced; some were published elsewhere whilst unpublished proofs and archive notes survive for others. From these various sources the volume as planned by Bruce can be reconstructed. The key contributor was J. H. H. Pirie, a medical doctor and primarily the expedition's surgeon. Despite his limited relevant experience his geological observations were commendable, with the notable exception of an important palaeontological misidentification that was inexplicably supported by eminent British experts. The archive material illuminates the background to Pirie's contributions and the ways in which his unpublished work came to be preserved.

Theudium Austroatlanticum (Verrucariaceae), A New Species from the South Orkney Islands

1993 ◽  
Vol 25 (3) ◽  
pp. 271-277 ◽  
Author(s):  
Alan Orange
Keyword(s):  
New Species ◽  
The South ◽  
Orkney Islands ◽  
Signy Island ◽  
South Orkney Islands ◽  
A New Species

AbstractThelidium austroatlanticum sp. nov. is described from Signy island; it is characterized by an epilithic thallus, more or less appressed involucrellum, and 1-septate spores 30–40 μm long. Thelidium incavatum is also reported for Signy Island.

scholarly journals Using habitat models to identify marine important bird and biodiversity areas for Chinstrap Penguins Pygoscelis antarcticus in the South Orkney Islands

Polar Biology ◽  
2018 ◽  
Vol 42 (1) ◽  
pp. 17-25 ◽  
Author(s):  
M. P. Dias ◽  
V. Warwick-Evans ◽  
A. P. B. Carneiro ◽  
C. Harris ◽  
B. G. Lascelles ◽  
...  
Keyword(s):  
The South ◽  
Habitat Models ◽  
Orkney Islands ◽  
Pygoscelis Antarcticus ◽  
South Orkney Islands

Cell osmotic water permeability of isolated rabbit proximal straight tubules

1982 ◽  
Vol 242 (4) ◽  
pp. F321-F330 ◽  
Author(s):  
E. Gonzalez ◽  
P. Carpi-Medina ◽  
G. Whittembury
Keyword(s):  
Surface Area ◽  
Water Flow ◽  
Water Permeability ◽  
Permeability Coefficient ◽  
Osmotic Water Permeability ◽  
Water Permeability Coefficient ◽  
Osmotic Water ◽  
Straight Tubules ◽  
Tubular Surface ◽  
Set Up

Proximal straight tubules were dissected and mounted in a chamber with their lumina occluded. The well-stirred bath could be 95% changed within 84 ms to set up osmotic gradients (delta Coi) across the peritubular cell aspect. Volume changes (less than or equal to 10 pl/mm) were estimated from continuous records of diameter changes (error less than 0.1 micrometers). delta Coi greater than or equal to 2-3 mosM could be discerned. delta Coi values from 10 to 44 mosM were used to evaluate Posc, the cell osmotic water permeability coefficient, and extrapolated to delta Coi = 0. Posc = 25.1 (+/- 2.3) X 10(-4) cm3.s-1.osM-1.cm2 tubular surface area-1. These values are lower than those reported for Pose, the transepithelial osmotic water permeability coefficient, and become lower if corrected for the real (infolded) peritubular cell surface area. Thus, for a given osmotic difference, transcellular water flow finds a higher resistance than paracellular water flow. Experiments were also performed with delta Coi greater than 100 mosM, but interpretation of these data is difficult because of the presence of volume regulatory phenomena and other undesirable effects.

High-pressure medium-temperature metamorphism of semi-pelitic rocks in the Scotia Metamorphic Complex, Powell Island, South Orkney Islands, Antarctica

2019 ◽  
Vol 91 ◽  
pp. 8-26
Author(s):  
Rodrigo Vinagre da Costa ◽  
Renato de Moraes ◽  
Rudolph Allard Johannes Trouw ◽  
Luiz Sérgio Amarante Simões ◽  
Julio Cezar Mendes
Keyword(s):  
High Pressure ◽  
Metamorphic Complex ◽  
Medium Temperature ◽  
Orkney Islands ◽  
South Orkney Islands ◽  
Pressure Medium ◽  
Pelitic Rocks

Conservation on the High Seas: Developing the Concept of the High Seas Marine Protected Areas

2012 ◽  
Vol 27 (4) ◽  
pp. 849-857 ◽  
Author(s):  
Karen N. Scott
Keyword(s):  
Protected Areas ◽  
Marine Protected Areas ◽  
General Assembly ◽  
Orkney Islands ◽  
South Orkney Islands ◽  
National Jurisdiction ◽  
Un General Assembly ◽  
The Creation ◽  
The Relationship ◽  
High Seas

Abstract This article explores developments in connection with marine protected areas (MPAs) on the high seas, beginning with a brief survey of existing high seas MPAs, recent initiatives such as the designation of the South Orkney Islands MPA, the creation of a network of OSPAR MPAs and the work undertaken by the UN General Assembly on developing a framework for oceans governance in areas beyond national jurisdiction. It considers: the absence of a clear legal basis for the creation of MPAs on the high seas; the relationship between MPA designation and traditional high seas freedoms; and the complex jurisdictional arrangements that govern activities on and in the high seas.

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