Analysing migrations of Atlantic cod Gadus morhua in the north-east Atlantic Ocean: then, now and the future.

The application of data storage tags bears the potential for a quantum leap in the research on fish migrations, because not only first-capture and recapture positions are known, but at least theoretically, the migration path during the period at large can be reconstructed. Position, however, cannot be measured directly but has to be estimated using the available data on light, temperature, pressure and salinity. The reconstructed locations based on advanced estimation techniques have been termed geolocations. Examples are discussed which illustrate the applicability of geolocations in individual path descriptions, separation of reproductively isolated populations, timing and areas of spawning, tidal transport and use of protected areas. The examples are based on archival tag data from the North Sea, the Baltic Sea, the Barents Sea and Faroese and Icelandic Waters. Besides presenting the state-of-the-art geolocations for cod Gadus morhua in the north-east Atlantic Ocean, the major aim of this review is to raise awareness of gaps in knowledge and to identify ideas for new research.

Recovery of gastric evacuation rate in Atlantic cod Gadus morhua L surgically implanted with a dummy telemetry device.

The current study investigated how the gastric evacuation rate (GER) was affected after surgically introducing dummies of a blood flow biotelemetry system into the abdominal cavity of Atlantic cod, Gadus morhua. Gastric evacuation experiments were performed two and 10 days postsurgery on surgically implanted and control G. morhua force-fed sandeel, Ammodytes tobianus. The results were compared with previously obtained estimates from unstressed conspecifics voluntarily feeding on a similar diet. After two days, GER was significantly lower in the group of fish with the dummy implants compared with the control group, but following 10 days of recovery no significant difference was seen between the two groups. The difference between implanted and control fish observed two days postsurgery may have resulted either from surgery, postsurgical stress and/or the presence of the implant. The conclusion is that 10 days of postsurgical recovery will stabilize GER in G. morhua, thus indicating that at this point the implant per se did not affect GER. Both the fish with surgical implants and controls in this study evacuated their stomachs much slower and with much higher interindividual variation compared with G. morhua feeding voluntarily on similar prey items. The lower GER and higher interindividual variation for force-fed fish indicate that handling, anaesthetization and force-feeding impair GER and that individual fish respond differently to the suppressing effects.

Some Atlantic cod Gadus morhua in the Baltic Sea visit hypoxic water briefly but often.

Individual behaviour of Atlantic cod Gadus morhua in the presence of hypoxic water was measured in situ in the vertically stratified Bornholm Basin of the Baltic Sea. Considering all recaptured individuals, the use of hypoxic habitat was comparable to data derived by traditional survey data, but some G. morhua had migrated towards the centre of the c.100 m deep basin and spent about a third of their time at oxygen saturation <50%, possibly to forage on zoobenthos. Maximal residence time per visit in such hypoxic water was limited to a few hours, allowing for the digestion of consumed prey items in waters with sufficient dissolved oxygen.

Survival of macroencapsulated allogeneic parathyroid tissue one year after transplantation in nonimmunosuppressed humans.

The use of immunoisolation devices may allow transplantation without need for immunosuppression and could widen the indications for cell transplantation. In this study, we evaluated the survival of encapsulated parathyroid tissue in nonimmunosuppressed humans. Autologous parathyroid implants: Seven patients undergoing parathyroidectomy had devices containing small pieces of their own parathyroid tissue implanted SC. These devices were explanted after 2-4 weeks for histological evaluation. Allogeneic parathyroid implants: Four patients with chronic hypoparathyroidism were transplanted with one to three large (40 microl) and one small (4.5 microl) device filled with meshed parathyroid tissue and implanted SC. The small devices were explanted at 4 weeks, while the large ones were explanted 8.5 to 14 months after implantation. In both studies, control implants were placed in nude mice. Autologous study results: At explantation, the grafts consisted of 22 +/- 6% endocrine tissue and 63 +/- 7% fibrosis, while 15 +/- 5% of the grafts were necrotic. Allogeneic study results: In devices explanted from the patients at 4 weeks, fibrosis dominated and only 1%, 5%, and 23% of the grafts consisted of endocrine tissue. A similar histological appearance was found in grafts from nude mice. In devices explanted at 8.5-14 months, histologically intact endocrine tissue was found in all patients. However, nearly all the tissue consisted of fibrosis. There was no detectable increase in the parathormone (PTH) level in all patients. Macroencapsulated human allogeneic parathyroid tissue can survive up to 1 year after transplantation into nonimmunosuppressed patients. However, marked fibroblast overgrowth occurred, especially in the allogeneic implant study, using meshed parathyroid tissue. This was probably not related to the allo-response, because similar findings were observed in the nude mouse implants. In future studies, better tissue preparation and improvements in the physiological milieu inside the device may help to reduce fibroblast overgrowth and increase survival of the parathyroid cells.

Immunoisolation of tumor cells: generation of antitumor immunity through indirect presentation of antigen.

In recent years, a number of cancer therapies have been developed based on the augmentation of the immune response in the tumor-bearing individual. We have developed a novel approach to such therapies, using a membrane-bound immunoisolation device containing tumor cells to enhance the immune response of mice to the adenocarcinoma, MCA-38. Use of an immunoisolation device for cancer immunotherapy has several advantages. First, safety is enhanced because the reintroduced tumor cells are sequestered within the device. Second, the immunoisolation device permits introduction and maintenance of live cells that can stimulate the immune system for extended periods. Finally, the cells can be quantitatively removed at the end of the treatment period. Cells derived from the murine adenocarcinoma cell line MCA-38 were implanted into mice within a membrane-enclosed (immunoisolation) device. After 3 weeks, the animals were challenged by injection of free tumor cells. All of the control animals (lacking implants or with empty devices) developed tumor at the challenge site, whereas all of the animals that received devices containing tumor cells remained tumor free. The animals also remained tumor free after a second challenge. It is our hypothesis that antigens shed from tumor cells within the device are taken up by antigen-presenting cells of the host and thus indirectly initiate the activation of the immune system.